[iOS] Handle multiple scenes #20502
Description
Is your feature request related to a problem? Please describe.
#20454 added the scene-based lifecycle to iOS applications.
However, it was only done in a compatible way, supporting a single view.
Avalonia should handle multiple scenes, and multiple windows and views.
Describe the solution you'd like
Implement multiple scene handling in iOS.
Describe alternatives you've considered
No response
Additional context
No response