Implement flutter version of withLeakTracking that calls MemoryAllocations.instance.addListener

[JulianBissekkou]

To be able to catch flutter framework memory leaks we have to call MemoryAllocations.instance.addListener which does not happen in withLeakTracking.
I understand if withLeakTracking should be framework independent but then we should update the documentation 👍🏽

[polina-c]

leak_tracker is a pure Dart library, while MemoryAllocations is a Flutter class.
withLeakTracking states in documentation that, if you use Flutter, the invocation should happen.

There should be separate method for Flutter to track Flutter leaks. While it is not implemented yet, you can create your own in your project.

[polina-c]

Discussion: flutter/devtools#3951 (comment)

The plan is to create leak_tracker_flutter in the same mono-repo, but publishing it out of the flutter.dev publisher. @devoncarew , are you still ok with this option? If yes, I will prepare PR to create this package and also address #78.

[devoncarew]

For these three options:

package:leak_tracker_flutter published in tools.dart.dev, and banking on 'flutter' in the name being clarifying enough

I think we want to avoid having dart.dev published packages depending on the flutter sdk.

keeping leak_tracker_flutter in the same mono-repo, but publishing it out of the flutter.dev publisher

This one would be ok (publishing from flutter.dev but hosting the code in a dart-lang mono-repo). We just want to make sure that we don't take a dependency on this package from the dart-lang/sdk repo - this is a possibility as the leak_tracker repo is dep'd into the sdk.

putting the code in the flutter/packages mono-repo and using the flutter.dev publisher

I don't see any real downsides to this from a hygiene POV. It would mean that the leak tracker related code was spread across a few repos, which may not be desired.