Fix letterbox and orientation request on DisplayAreaGroup

Before, with a multi displayarea policy setting, fixed-orientation app
may have incorrect bounds.

1. CompatDisplayInsets: use RootDisplayArea bounds as the mWidth and
   mHeight
2. onDescendantOrientationChanged: stop calling super method if ignore,
   otherwise it can return true from DC even though DAG is ignored. We
   want it to be hanled by Task in such case.
3. DAG should adjust the configuration orientation based on its
   dimensions, so a width > height DAG is considered landscape.
4. getRequestedConfigurationOrientation() should only reverse the
   orientation at DC level, so that Task and ActivityRecord can handle
   the bounds based on the request correctly.
5. Compare app bounds with RootDisplayArea bounds to check whether it
   is letterboxed.

Bug: 155431879
Test: manual: test with a dual displayarea policy
Test: atest WmTests:SizeCompatTests
Test: atest WmTests:DisplayAreaTest
Test: atest WmTests:DisplayAreaGroupTest
Change-Id: I16277cb9984c87ed4bcd50b91e0d12c2c6bbd5b1