Update to Microsoft.WindowsAppSDK 1.6, enable AoT.

Tracking issue for updating toolkit tooling to WindowsAppSDK 1.6 and enabling AoT support.

Preview1:
- Tooling: https://github.com/CommunityToolkit/Tooling-Windows-Submodule/pull/195
- Windows Community Toolkit https://github.com/CommunityToolkit/Windows/pull/457
- Windows Community Toolkit Labs https://github.com/CommunityToolkit/Labs-Windows/pull/561

Preview2:
- Tooling: https://github.com/CommunityToolkit/Tooling-Windows-Submodule/pull/208
- Windows Community Toolkit https://github.com/CommunityToolkit/Windows/pull/492
- Windows Community Toolkit Labs https://github.com/CommunityToolkit/Labs-Windows/pull/568

Stable:
- Tooling: https://github.com/CommunityToolkit/Tooling-Windows-Submodule/pull/209
- Windows Community Toolkit https://github.com/CommunityToolkit/Windows/pull/503
- Windows Community Toolkit Labs https://github.com/CommunityToolkit/Labs-Windows/pull/570

CsWinRTAotWarningLevel 2:
- Tooling: https://github.com/CommunityToolkit/Tooling-Windows-Submodule/pull/212
- Windows Community Toolkit https://github.com/CommunityToolkit/Windows/pull/507
- Windows Community Toolkit Labs https://github.com/CommunityToolkit/Labs-Windows/pull/572

General Gallery / Component issues:
- https://github.com/CommunityToolkit/Tooling-Windows-Submodule/issues/213
- https://github.com/CommunityToolkit/Windows/issues/509
- https://github.com/CommunityToolkit/Windows/issues/510
- https://github.com/CommunityToolkit/Windows/issues/511
- https://github.com/CommunityToolkit/Windows/issues/512
- https://github.com/CommunityToolkit/Windows/issues/513
- https://github.com/CommunityToolkit/Windows/issues/514
- https://github.com/CommunityToolkit/Windows/issues/515
- https://github.com/CommunityToolkit/Windows/issues/516
- https://github.com/CommunityToolkit/Windows/issues/517
- https://github.com/CommunityToolkit/Windows/issues/519
- #215