[37/n] Create TransitionObserver for LifecycleController

A new TransitionObserver implementation which delegates to
the LifecycleController.

Flag: com.android.window.flags.app_compat_refactoring
Bug: 409951586
Test: atest WMShellUnitTests:MigrationLetterboxTransitionObserverTest
Test: atest WMShellUnitTests:DelegateLetterboxTransitionObserverTest

Change-Id: Id5b0754bcfb411e053ffe5a2834710ffc3e201ca