[46/n] Implement SkipLetterboxLifecycleEventFactory

SkipLetterboxLifecycleEventFactory allows to skip the Change in a
TransactionObserver which is not useful for the Letterbox Surfaces
lifecycle.

The current implementation ignores transitions related to
Desktop Windowing.

Flag: com.android.window.flags.app_compat_refactoring
Bug: 309593314
Fix: 420552293
Test: atest WMShellUnitTests:SkipLetterboxLifecycleEventFactoryTest

Change-Id: I4e9afb9c85db680f06afa54fae9541f6cea8264d