Extend test coverage

[aumetra]

Extending the test coverage of the following sub-crates:

• geomjeungja
• masto-id-convert
• speedy-uuid
• tower-http-digest

[codecov]

Codecov Report

Attention: Patch coverage is 98.80952% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 31.39%. Comparing base (b023a12) to head (cd4ac5f).

❗ Current head cd4ac5f differs from pull request most recent head 9c0b5a2. Consider uploading reports for the commit 9c0b5a2 to get more accurate results

Files	Patch %	Lines
lib/speedy-uuid/src/lib.rs	98.18%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #505      +/-   ##
==========================================
+ Coverage   30.58%   31.39%   +0.81%     
==========================================
  Files         330      330              
  Lines       16517    16600      +83     
==========================================
+ Hits         5051     5212     +161     
+ Misses      11466    11388      -78     

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[aumetra]

Last piece I want to test is the mrf-manifest crate and its parsing functionalities. Luckily that will be pretty easy using the wat crate and some manual WASM in text format.
Similar testing approach to what we use at CosmWasm.

After that we can merge this and focus on the restructure.