Fix MAUI MapControl memory leak (SKGLView not released after navigation) - #3273

Thanks for the PR — the problem is real and the fixes are correct.

What's good:

• RenderController.Dispose() now unblocks the render loop (the .Set() calls are a genuine bug fix)
• DataFetcher getting IDisposable with cancellation is the right approach
• Android FixInvisible() infinite loop getting a CancellationToken is a clear improvement
• MAUI handler disconnection via DisconnectHandler() is the correct MAUI pattern

Minor notes:

• OpenInBrowserStatic is added in the constructor but SharedConstructor() already calls SetOpenInBrowserFunc — results in a redundant double call
• TryStopMyLocationAnimations() — the "Try" prefix implies error tolerance that isn't there; StopMyLocationAnimations() would be more accurate
• CleanupMapViewResources() calls Map.Layers.Clear() before base.Dispose() also clears layers — harmless but redundant

Architectural note:
The disposal code is now correct, but users still need to call Dispose() explicitly on navigation. A follow-up worth considering: overriding OnHandlerChanged() on the MAUI MapControl to call Dispose() automatically when Handler == null — that's the idiomatic MAUI lifecycle pattern and would make this fully transparent to users. This is something for a future PR.