Resolves: Add a CI pipeline with GitHub Actions

[aleks-ivanov]

The pipeline runs:

1. CI

• build and unit tests validation
• debug assemblies and unit tests results generation
• uploading artifacts to pipeline run (checkout the PR run of the pipeline for artifact download)

File changes:

• Code change in src/TestTargets/Types/Types.csproj is because of this error:

/workspaces/clrmd/src/TestTargets/Types/obj/Debug/netcoreapp3.1/Types.AssemblyInfo.cs(15,12): error CS0579: Duplicate 'System.Reflection.AssemblyFileVersionAttribute' attribute [/workspaces/clrmd/src/TestTargets/Types/Types.csproj]
/workspaces/clrmd/src/TestTargets/Types/obj/Debug/netcoreapp3.1/Types.AssemblyInfo.cs(19,12): error CS0579: Duplicate 'System.Reflection.AssemblyVersionAttribute' attribute [/workspaces/clrmd/src/TestTargets/Types/Types.csproj]

Additions:

We would like to add Continuous Deployment as well, however we know there are internal procedures often incorporated with Microsoft projects for the packaging, so we wanted to confirm first if what we have as an idea is desirable. The CD would include:

• commit-based automated versioning
• NuGet package generation and signing
• deployment to NuGet.org
• creation of GitHub Release

Please let us know if you'd like us to include that, if anything could be done better and/or if any other automation is required by the project! We would be happy to improve it to satisfactory completion 🙂

Resolves #943