Push notifications down offscreen when QQS expands to fullscreen QS

And bring notifications back up when fullscreen QS closes to QQS

This updates UI to spec and fixes issues where the top of the
notifications background scrim and notification shelf icons still show
in fullscreen QS, which looks messy and blocks the media player.

Fixes: 187195324
Test: open shade, expand QS, close QS, close shade
Change-Id: Ic0a3238db16086ac272e80521c5e332d1a92744b