Implement WinUI

[AliveDevil]

For the samples following applies:

• Requires Project Reunion 0.8 stable sdk

• Requires Single Project MSIX-support package

As the regular implementation does not depend on WinUI (only the nuget package for references) I don't think this requires any knowledge of WinUI/Project Reunion/Windows App SDK

Implements #29

[CLAassistant]

All committers have signed the CLA.

[Lakritzator]

I created a new branch (feature/WinUI), and targeted this PR to it, which allows us to play with it before putting it into master.

[AliveDevil]

From my side there is nothing to be added here.
It Works™️ for now, doesn't crash on my side with this code.
Will need revision for Windows App SDK 1.0.

[Lakritzator]

Ok, cool, I will try it out as soon I as have some time.

[kevinchalet]

That would be awesome to see this PR merged ❤️‍🔥

[AliveDevil]

That would be awesome to see this PR merged ❤️‍🔥

I’ll see that I get it up to date and working next week.

[AliveDevil]

Updated to latest stable WindowsAppSdk 1.2 (instead of ProjectReunion), included net6 as well (WAppSdk requires at least net6-windows10.0.17763).
Tried starting any of the Packaged-projects (separate Packaging-project & Single-Packaged Project).

@Lakritzator anything left for this to get testing done?