Add AOT Compatibility

[simonrozsival]

Description of Change

This PR marks all product assemblies as AOT-compatible and fixes all warnings produced by trim and AOT analyzers. The list of warnings was surprisingly short:

• BaseBehavior.IsBound is inherently trim-unsafe, but since it's already [Obsolete], I think it is OK to just mark it as [RequiresUnreferencedCode] (any app or library which would call this method will get a trimming warning and will have to deal with it)
• ServiceCollectionExtensions methods need [DynamicallyAccessedMembers] attributes matching IServiceCollection
• PopupService.AddTransientPopup needs [DynamicallyAccessedMembers] attributes matching IServiceCollection
• ValueConverterExtension.IsValidTargetType is the most complicated case I think. It is not possible to fix this case with [DAM] attributes because as I propagated the attribute to all callsites, I reached a point where I would need to add the attribute to Microsoft.Maui.Controls.IValueConverter which wasn't possible. I tried to simplify the method, because it seemed too complicated. I'll leave some comments in the code to explain my reasoning.

TODO (incomplete list)

• Fix Windows specific warnings (PopupExtensions.SetColor, JSON deserialization in MapHandler
• Remove all uses of new Binding(...) in favor of expression-based bindings (not available yet, still WIP in MAUI)
• Update type converters of types which define implicit operators (FileMediaSource, MediaSource, ResourceMediaSource, UriMediaSource)

Linked Issues

• Fixes [Proposal] Add Support for NativeAOT #1509

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls

Additional information

[TheCodeTraveler]

Thanks for getting this started @simonrozsival!

I confirmed our Sample App runs on iOS when <PublishAOT>enabled</PublishAOT> with no problems.

[simonrozsival]

@brminnick thanks a lot for finishing the PR!