[Epic] Add other packages from @actions/toolkit

[IEvangelist]

The following is a table of new NuGet packages to add:

• Add GitHub.Actions.HttpClient: equivalent to @actions/http-client. Add Actions.HttpClient #9
• Add GitHub.Actions.Exec: equivalent to @actions/exec. Consider CliWrap.
• Add GitHub.Actions.UploadArtifact: equivalent to @actions/upload-artifact. Add Actions.Artifact #4
• Add GitHub.Actions.DownloadArtifact: equivalent to @actions/download-artifact. Add Actions.Artifact #4
• Add GitHub.Actions.Cache: equivalent to @actions/cache.
• Add GitHub.Actions.ToolCache: equivalent to @actions/tool-cache.
• Add GitHub.Actions.Attest: equivalent to @actions/attest.

Consider adding a metapackage to bring in all of these packages. Each additional NuGet package should be developed one at a time, and contain the following characteristics:

• DI-friendly usage and non-DI usage
• README with examples, using the existing toolkit package's README.md as inspiration
• Corresponding test project within the ./tests directory
• Appropriate attribution and thanks of OSS projects that are being used
• Considerations for test-utilities per project that expose test implementations, or easily allow for testing