Make Desktop WPF use Core WPF targets and tasks (MarkupCompile)

Currently when you build a WPF application for `net472` and use legacy WPF, it imports `C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Xaml.targets`:


The targets are legacy and haven't been updated. For example, GenerateTemporaryTargetAssembly task doesn't have the latest properties:


We need to stop relying on things from C:\Windows, for hermetic and isolated builds. Moving to the same targets and tasks in the SDK instead ensures portability (you could build WPF desktop projects on Mac, for example) and future-proofs them.

Bonus: see if it's possible to use the new WPF assemblies for `net472` desktop applications, instead of the ones shipping in .NET Framework. If possible, this would allow to prepare WPF apps for moving to .NET Core.