Merge changes from topic "safe-region-letterboxing" into main

* changes:
  [7/n] Add application and activity property to allow safe region letterboxing
  [6/n] Apply the safe region bounds WCT
  [5/n] Integrate AppCompatSafeRegionPolicy in LaunchParams
  [4/n] Apply AppCompatSafeRegionPolicy during activity launch
  [3/n] Add safe region bounds in WindowContainer
  [2/n] Create AppCompatSafeRegionPolicy for letterboxing
  [1/n] Add WCT for setting safe region bounds for letterboxing