Update Microsoft.WindowsAppSDK to 1.6-preview2

[Arlodotexe]

This PR updates our tooling to use Microsoft.WindowsAppSDK 1.6-preview2 and removes prior workarounds only needed for preview1.

Prerequisite PR: CommunityToolkit/Tooling-Windows-Submodule#208

[michael-hawker]

@Arlodotexe is there anything that's blocking us from merging the preview2 updates?

[Arlodotexe]

@Arlodotexe is there anything that's blocking us from merging the preview2 updates?

Nothing blocking us from merging, CI seems to be all green and it's working well deployed locally.

Was hoping to use this PR to enable and work through the additional CsWinRTAotWarningLevel analyzer warnings suggested by Sergio here, in the last PR.

[Arlodotexe]

@Arlodotexe is there anything that's blocking us from merging the preview2 updates?

Nothing blocking us from merging, CI seems to be all green and it's working well deployed locally.

Was hoping to use this PR to enable and work through the additional CsWinRTAotWarningLevel analyzer warnings suggested by Sergio here, in the last PR.

With 1.6 stable out now, we'll do this in a separate PR to keep things moving.

[michael-hawker]

Approved to unblock you once the tooling submodule is updated