Implement MinVer to use proper Version Numbers

[Stelzi79]

• updated Microsoft.NET.Test.Sdk to latest stable 16.7.1
• implemented MinVer to automatically set all the Version numbers plus some special BuildMetadata when it is not from the main branch or a release. See parsers/dotnet/Directory.Build.props for more details about it.
• On a release it takes the VERSION_STATIC environment variable and overrides any other calculated version number.

I've tested all the GitHub actions in my Fork and even tested the NuGet workflow publish. it perfectly published it to Nuget Stelzi79.TAML (unlisted!)! See also the run of the Workflow on my fork (publish to nuget) and the run of the normal build task (.NET Core)

[Stelzi79]

Also if you want to do it without this particular NuGet publish action simply setting the MinVerVersionOverride environment variable tells MinVer which Version it should use instead the one it calculates. MinVer normally calculates the version from the last Git tag and then counts up the commits between the current and the commit with the tag. A GitHub release is nothing more than a fancy UI to add a Git tag IMO.