Avalonia.GameStudio

Proof of concept for having the Xenko GameStudio running on Avalonia UI (xplat).

/!\ This is a work in progress. /!\

Provisional plan

1. Make a vanilla Avalonia application
2. Open a Xenko project with it
3. Integrate more and more features until it reach read-only parity with current GameStudio
4. Integrate a game view
5. Allow changes