Support SwapChainPanel on Windows

[DDRBoxman]

Is your feature request related to a problem? Please describe.

I've been exploring how to render to a view in a WinUI3 application and after some investigation there doesn't seem to be a good way to do that currently.

Describe the solution you'd like

Ideally Instance would have an additional function that could take in a SwapChainPanel and set the swap chain on it.

Describe alternatives you've considered

I tried using Microsoft.UI.Content.ContentExternalOutputLink.PlacementVisual but not only is that only experimental it also requires building a hwind outside the application and then you have to hide that window somehow.

I also tried passing a null Visual to Instance with instance.create_surface_from_surface_handle on windows and that let me build the rendering context without a surface. The plan was to pass the dx12 swap chain back up to C# but the fields in dx12 are private.

Additional context

https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.controls.swapchainpanel.-ctor?view=windows-app-sdk-1.4

[DDRBoxman]

I got a proof of concept working this afternoon, it ended up being a little backwards to test the feasibility but I’ll look into cleaning it up properly and submitting a PR