TaskCanceledException on IStreamImageSource.GetStreamAsync(CancellationToken userToken)

My app has an BackgroundImageSource loaded on ctor with the code bellow

```
var imageBytes = System.IO.File.ReadAllBytes(filePath);
if (imageBytes == null)
return;

this.BackgroundImageSource = ImageSource.FromStream(() => new MemoryStream(imageBytes));
```

The method FireAndForget is responsible for applying the image to the UI.

Uncoordinated image loading and UI lifecycle events, compounded by inadequate `TaskCanceledException` handling in `FireAndForget`.


```
/_/src/Controls/src/Core/StreamImageSource.cs in async Task StreamImageSource.Microsoft.Maui.IStreamImageSource.GetStreamAsync(CancellationToken userToken) at line 43:5

/_/src/Controls/src/Core/StreamImageSource.cs in async Task StreamImageSource.Microsoft.Maui.IStreamImageSource.GetStreamAsync(CancellationToken userToken) at line 49:5

/_/src/Core/src/ImageSources/StreamImageSourceService/StreamImageSourceService.Android.cs in async Task> StreamImageSourceService.GetDrawableAsync(IImageSource imageSource, Context context, CancellationToken cancellationToken) at line 76:6

/_/src/Core/src/Platform/Android/ViewExtensions.cs in async Task ViewExtensions.UpdateBackgroundImageSourceAsync(View platformView, IImageSource imageSource, IImageSourceServiceProvider provider) at line 422:5

/_/src/Core/src/TaskExtensions.cs in async void TaskExtensions.FireAndForget(Task task, Action errorCallback) at line 36:5
```

When the application navigates to a new page, triggering the `Appearing` lifecycle event, which initiates the image loading process.

This is where the image loading is triggered, setting the stage for the race condition

I've created an PR to fix this
https://github.com/dotnet/maui/pull/28685

Start with src/Controls/src/Core/StreamImageSource.cs and follow the reported stack through StreamImageSourceService.Android.cs, ViewExtensions.cs, and TaskExtensions.cs. Review the proposed fix in PR #28685, then run the reported navigation and image-loading scenario; done means the cancellation no longer produces the reported unhandled exception.

Written by the indexing model from the issue text.