* Ensure PackageArchive contains the right build of Razor.Design package
* Re-order values in build\dependencies.props to ensure Razor.Design's package version is
overwritten.
* Convert additional package refs to project refs
Fixes https://github.com/aspnet/AspNetCore-Internal/issues/1708
* Update CodeCheck.ps1
.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.