CI/CD test and publish to NuGet

[ashtonmeuser]

Simple GitHub Action workflow to run tests and publish to NuGet. @nuskey8 This will require an API key stored as a secret. Runs on pushing a semver tag e.g. v0.5.4 or via explicit workflow dispatch.

This PR also throws the ExpectedFailure onto several of the test files inherited from Lua proper so we can skip them during CI. Note that additional test cases would require ExpectedFailure unless #279 is merged.

[ashtonmeuser]

This still requires updating Directory.Build.props with the correct version number. A nice-to-have improvement may be validating this version against the pushed tag.

Edit: I actually found that the versions had diverged already. See Directory.Build.props (0.5.3) and src/Lua.Unity/Assets/package.json (0.5.1). Added the version check.