Migrate to Vortice.Windows

[hez2010]

What does the pull request do?

Migrate from SharpDX to Vortice.Windows.

Supersedes #7947

What is the current behavior?

Relying on SharpDX which is no longer being maintained.

Breaking changes

Avalonia.Direct2D no longer supports net6.0 and lower.

[kekekeks]

Why would we want to break .NET Framework support? Are there known problems with SharpDX that affect Avalonia-based apps? IIRC it was covering the required D2D API surface and was trimming-friendly.

[hez2010]

The D2D1 backend has been broken for long time since we introduced the compositing renderer (it doesn't work at all and throws an exception immediately before #15610, and even after the fix, it's still not working and results in bad visuals on the UI), so I believe there's no existing user who is using it. Dropping the .NET Framework support for this specified package seems fine as it won't break anyone.
By migrating to Vortice.Windows we can get more bug fixes and support for latest DirectX version in case we want to implement a D3D11/D3D12 renderer in the future (which can also help us get rid of gles and skia on Windows to save ~20mb binary size).