Add field and rule value to violations (#64)

Adds the ability to access the captured rule and field value from a
Violation.

C++ protobuf doesn't really have a native "value" representation unlike
other languages, so I've created a sort-of stand-in. The `ProtoField`
class acts as a reference to a field on a message, and provides an
interface to get a singular value as a `variant`. This should be good
enough for most users, but users can also grab the information needed
and use protobuf reflection directly instead if they have more
complicated needs.

**This is a breaking change.** The API changes in the following ways:
- `Validator::Validate()` now returns the wrapper type
`ValidationResult` instead of `Violations`. This can be converted into
the protobuf `Violations` form using the `proto()` method.
- `ValidationResult.violations()` returns a `ConstraintViolation`. The
underlying `Violation` can be accessed using the `proto()` method.

Implement predefined field constraints (#61)

Like protovalidate-go and protovalidate-java, we need to adjust the code
to handle dynamic descriptor sets more robustly, since we need to jump
between resolving the protovalidate standard rules and the predefined
rule extensions. This necessitates adding a couple of additions to the
API surface, namely `ValidatorFactory::SetMessageFactory` and
`ValidatorFactory::SetAllowUnknownFields`, which controls instantiation
of unknown dynamic types and whether or not to ignore unresolved rules,
respectively. Like other protovalidate runtimes, we will default to
failing compilation when unknown predefined rules are encountered. This
should not break existing users but will prevent silent incorrect
behavior.

TODO:
- [x] Skip reparse when there are no empty fields—this way we can
avoid pessimizing the common case
- [x] Add an option to fail when unknown rule fields are unable to be
resolved.
- [x] Update for protobuf changes in
bufbuild/protovalidate#246.

This will depend on bufbuild/protovalidate#246.

Bump actions/cache from 3 to 4 (#51)

Bumps [actions/cache](https://github.com/actions/cache) from 3 to 4.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a
href="https://github.com/actions/cache/releases">actions/cache's
releases</a>.</em></p>
<blockquote>
<h2>v4.0.0</h2>
<h2>What's Changed</h2>
<ul>
<li>Update action to node20 by <a
href="https://github.com/takost"><code>@​takost</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1284">actions/cache#1284</a></li>
<li>feat: save-always flag by <a
href="https://github.com/to-s"><code>@​to-s</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1242">actions/cache#1242</a></li>
</ul>
<h2>New Contributors</h2>
<ul>
<li><a href="https://github.com/takost"><code>@​takost</code></a> made
their first contribution in <a
href="https://redirect.github.com/actions/cache/pull/1284">actions/cache#1284</a></li>
<li><a href="https://github.com/to-s"><code>@​to-s</code></a> made their
first contribution in <a
href="https://redirect.github.com/actions/cache/pull/1242">actions/cache#1242</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a
href="https://github.com/actions/cache/compare/v3...v4.0.0">https://github.com/actions/cache/compare/v3...v4.0.0</a></p>
<h2>v3.3.3</h2>
<h2>What's Changed</h2>
<ul>
<li>Cache v3.3.3 by <a
href="https://github.com/robherley"><code>@​robherley</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1302">actions/cache#1302</a></li>
</ul>
<h2>New Contributors</h2>
<ul>
<li><a href="https://github.com/robherley"><code>@​robherley</code></a>
made their first contribution in <a
href="https://redirect.github.com/actions/cache/pull/1302">actions/cache#1302</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a
href="https://github.com/actions/cache/compare/v3...v3.3.3">https://github.com/actions/cache/compare/v3...v3.3.3</a></p>
<h2>v3.3.2</h2>
<h2>What's Changed</h2>
<ul>
<li>Fixed readme with new segment timeout values by <a
href="https://github.com/kotewar"><code>@​kotewar</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1133">actions/cache#1133</a></li>
<li>Readme fixes by <a
href="https://github.com/kotewar"><code>@​kotewar</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1134">actions/cache#1134</a></li>
<li>Updated description of the lookup-only input for main action by <a
href="https://github.com/kotewar"><code>@​kotewar</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1130">actions/cache#1130</a></li>
<li>Change two new actions mention as quoted text by <a
href="https://github.com/bishal-pdMSFT"><code>@​bishal-pdMSFT</code></a>
in <a
href="https://redirect.github.com/actions/cache/pull/1131">actions/cache#1131</a></li>
<li>Update Cross-OS Caching tips by <a
href="https://github.com/pdotl"><code>@​pdotl</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1122">actions/cache#1122</a></li>
<li>Bazel example (Take <a
href="https://redirect.github.com/actions/cache/issues/2">#2</a>️⃣) by
<a href="https://github.com/vorburger"><code>@​vorburger</code></a> in
<a
href="https://redirect.github.com/actions/cache/pull/1132">actions/cache#1132</a></li>
<li>Remove actions to add new PRs and issues to a project board by <a
href="https://github.com/jorendorff"><code>@​jorendorff</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1187">actions/cache#1187</a></li>
<li>Consume latest toolkit and fix dangling promise bug by <a
href="https://github.com/chkimes"><code>@​chkimes</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1217">actions/cache#1217</a></li>
<li>Bump action version to 3.3.2 by <a
href="https://github.com/bethanyj28"><code>@​bethanyj28</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1236">actions/cache#1236</a></li>
</ul>
<h2>New Contributors</h2>
<ul>
<li><a href="https://github.com/vorburger"><code>@​vorburger</code></a>
made their first contribution in <a
href="https://redirect.github.com/actions/cache/pull/1132">actions/cache#1132</a></li>
<li><a
href="https://github.com/jorendorff"><code>@​jorendorff</code></a> made
their first contribution in <a
href="https://redirect.github.com/actions/cache/pull/1187">actions/cache#1187</a></li>
<li><a href="https://github.com/chkimes"><code>@​chkimes</code></a> made
their first contribution in <a
href="https://redirect.github.com/actions/cache/pull/1217">actions/cache#1217</a></li>
<li><a
href="https://github.com/bethanyj28"><code>@​bethanyj28</code></a> made
their first contribution in <a
href="https://redirect.github.com/actions/cache/pull/1236">actions/cache#1236</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a
href="https://github.com/actions/cache/compare/v3...v3.3.2">https://github.com/actions/cache/compare/v3...v3.3.2</a></p>
<h2>v3.3.1</h2>
<h2>What's Changed</h2>
<ul>
<li>Reduced download segment size to 128 MB and timeout to 10 minutes by
<a href="https://github.com/kotewar"><code>@​kotewar</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1129">actions/cache#1129</a></li>
</ul>
<p><strong>Full Changelog</strong>: <a
href="https://github.com/actions/cache/compare/v3...v3.3.1">https://github.com/actions/cache/compare/v3...v3.3.1</a></p>
<h2>v3.3.0</h2>
<h2>What's Changed</h2>
<ul>
<li>Bug: Permission is missing in cache delete example by <a
href="https://github.com/kotokaze"><code>@​kotokaze</code></a> in <a
href="https://redirect.github.com/actions/cache/pull/1123">actions/cache#1123</a></li>
</ul>
<!-- raw HTML omitted -->
</blockquote>
<p>... (truncated)</p>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a
href="https://github.com/actions/cache/blob/main/RELEASES.md">actions/cache's
changelog</a>.</em></p>
<blockquote>
<h1>Releases</h1>
<h3>3.0.0</h3>
<ul>
<li>Updated minimum runner version support from node 12 -&gt; node
16</li>
</ul>
<h3>3.0.1</h3>
<ul>
<li>Added support for caching from GHES 3.5.</li>
<li>Fixed download issue for files &gt; 2GB during restore.</li>
</ul>
<h3>3.0.2</h3>
<ul>
<li>Added support for dynamic cache size cap on GHES.</li>
</ul>
<h3>3.0.3</h3>
<ul>
<li>Fixed avoiding empty cache save when no files are available for
caching. (<a
href="https://redirect.github.com/actions/cache/issues/624">issue</a>)</li>
</ul>
<h3>3.0.4</h3>
<ul>
<li>Fixed tar creation error while trying to create tar with path as
<code>~/</code> home folder on <code>ubuntu-latest</code>. (<a
href="https://redirect.github.com/actions/cache/issues/689">issue</a>)</li>
</ul>
<h3>3.0.5</h3>
<ul>
<li>Removed error handling by consuming actions/cache 3.0 toolkit, Now
cache server error handling will be done by toolkit. (<a
href="https://redirect.github.com/actions/cache/pull/834">PR</a>)</li>
</ul>
<h3>3.0.6</h3>
<ul>
<li>Fixed <a
href="https://redirect.github.com/actions/cache/issues/809">#809</a> -
zstd -d: no such file or directory error</li>
<li>Fixed <a
href="https://redirect.github.com/actions/cache/issues/833">#833</a> -
cache doesn't work with github workspace directory</li>
</ul>
<h3>3.0.7</h3>
<ul>
<li>Fixed <a
href="https://redirect.github.com/actions/cache/issues/810">#810</a> -
download stuck issue. A new timeout is introduced in the download
process to abort the download if it gets stuck and doesn't finish within
an hour.</li>
</ul>
<h3>3.0.8</h3>
<ul>
<li>Fix zstd not working for windows on gnu tar in issues <a
href="https://redirect.github.com/actions/cache/issues/888">#888</a> and
<a
href="https://redirect.github.com/actions/cache/issues/891">#891</a>.</li>
<li>Allowing users to provide a custom timeout as input for aborting
download of a cache segment using an environment variable
<code>SEGMENT_DOWNLOAD_TIMEOUT_MINS</code>. Default is 60 minutes.</li>
</ul>
<h3>3.0.9</h3>
<ul>
<li>Enhanced the warning message for cache unavailablity in case of
GHES.</li>
</ul>
<h3>3.0.10</h3>
<ul>
<li>Fix a bug with sorting inputs.</li>
<li>Update definition for restore-keys in README.md</li>
</ul>
<!-- raw HTML omitted -->
</blockquote>
<p>... (truncated)</p>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/actions/cache/commit/13aacd865c20de90d75de3b17ebe84f7a17d57d2"><code>13aacd8</code></a>
Merge pull request <a
href="https://redirect.github.com/actions/cache/issues/1242">#1242</a>
from to-s/main</li>
<li><a
href="https://github.com/actions/cache/commit/53b35c543921fe2e8b288765ff817de9de8d906f"><code>53b35c5</code></a>
Merge branch 'main' into main</li>
<li><a
href="https://github.com/actions/cache/commit/65b8989fab3bb394817bdb845a453dff480c2b51"><code>65b8989</code></a>
Merge pull request <a
href="https://redirect.github.com/actions/cache/issues/1284">#1284</a>
from takost/update-to-node-20</li>
<li><a
href="https://github.com/actions/cache/commit/d0be34d54485f31ca2ccbe66e6ea3d96544a807b"><code>d0be34d</code></a>
Fix dist</li>
<li><a
href="https://github.com/actions/cache/commit/66cf064d47313d2cccf392d01bd10925da2bd072"><code>66cf064</code></a>
Merge branch 'main' into update-to-node-20</li>
<li><a
href="https://github.com/actions/cache/commit/1326563738ddb735c5f2ce85cba8c79f33b728cd"><code>1326563</code></a>
Merge branch 'main' into main</li>
<li><a
href="https://github.com/actions/cache/commit/e71876755e268d6cc25a5d3e3c46ae447e35290a"><code>e718767</code></a>
Fix format</li>
<li><a
href="https://github.com/actions/cache/commit/01229828ffa049a8dee4db27bcb23ed33f2b451f"><code>0122982</code></a>
Apply workaround for earlyExit</li>
<li><a
href="https://github.com/actions/cache/commit/3185ecfd6135856ca6d904ae032cff4f39b8b365"><code>3185ecf</code></a>
Update &quot;only-&quot; actions to node20</li>
<li><a
href="https://github.com/actions/cache/commit/25618a0a675e8447e5ffc8ed9b7ddb2aaf927f65"><code>25618a0</code></a>
Bump version</li>
<li>Additional commits viewable in <a
href="https://github.com/actions/cache/compare/v3...v4">compare
view</a></li>
</ul>
</details>
<br />


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Add .bazelversion to pin Bazel version (#48)

This will prevent CI from unexpectedly breaking if a new Bazel release
has breaking changes.