[25/n] Handle animation for transparent activities

In case of transparent activities, the first opaque below needs
to be collected. In this case all the activities will need to be
animated in the LetterboxAnimationHandler

Flag: com.android.window.flags.app_compat_refactoring
Fix: 406181296
Test: atest WmTests:WindowContainerTransactionTests

Change-Id: Iff7d0c0b20a853c1d0273b52ca01459765586f83