Add new methods to ITaskStackListener

Refactor task change notification logic into a separate class
TaskChangeNotificationController.

Add ActivityManagerService.unregisterTaskStackChangedListener

Add a no-op implementation that clients can subclass to avoid
having to reimplement all new methods when they are added.

Add new methods:
onTaskAdded
onTaskRemoved
onTaskMovedToFront
onTaskDescriptionChanged
onActivityRequestedOrientationChanged
onTaskFinishing

Design doc:
https://docs.google.com/document/d/1IgWZ44rKe9k1CzkjP2Mohv12OgRD1FxH8oLAyzhvCY4/edit#heading=h.yhzl6os0dbo5

Cherry-picked from I8302d6d3baf1ac1ca928765fe203091b9fab4070

Bug: 32277482
Test: Verify that callbacks are called in dummy implementations

Change-Id: I2ac2b870147ef049f3ee05fc5916c99332334526