v5.0.0 Release Candidate 1

The new features are listed together in #311. The biggest pending change is to make a pass through the documentation to update it. There's also still time to respond to feedback between now and the official release.

What's Changed

• Groundwork in CMake, build workflows, and header include cleanup by @wravery in #312
• Add support for C++20 modules by @wravery in #313
• Additional cleanup from enabling C++20 modules by @wravery in #314
• minor std::format fixes by @wravery in #315
• feat(json): default taocpp-json impl for graphqljson by @wravery in #316
• feat(coro): update proxy client sample and improve async resolver throughput by @wravery in #317
• feat(sharedtypes): add clientgen --shared-types param to reuse types in schema by @wravery in #318

Full Changelog: v4.5.8...v5.0.0-rc1