* Update dependencies from https://github.com/dotnet/arcade build 20190423.2
- Microsoft.DotNet.GenAPI - 1.0.0-beta.19223.2
* Adjust to GenApi change in `enum` ordering
- was sorted by name, now by value
Changes:
* Add support for a property, `IsAspNetCoreApp`, in the .csproj file of assemblies which are part of the shared framework.
* Remove unused dependencies
* Remove reference which have become part of 'netcoreapp3.0'
.NET Core 2.0 reached EOL last year. This removes multi-targeting our test projects and test assets to only use .NET Core 2.1 and .NET Framework 4.6.1.