Update to WindowsAppSDK

[mattleibow]

This probably needs to be done before GA, but I was having some issues.

PR: #30665

Issue: microsoft/WindowsAppSDK#5626

I recall other issues or a crash, but did not get time to investigate.

[dotMorten]

Note: When moving to 1.8, make sure you change references from the Microsoft.WindowsAppSDK meta-package to the Microsoft.WindowsAppSDK.WinUI package so you no longer pull in everything.

Note that this will likely rely on 3rd party libraries to do the same, so logged:

• [FEATURE] Upgrade SkiaSharp.Views.WinUI to 1.8 mono/SkiaSharp#3372
• Update to WinAppSDK 1.8 microsoft/Win2D#1000