Fade out/in header with customizer in/out

As the QSPanel doesn't reach the top of the screen, the
LargeScreenShadeHeader peeks out from behind the Edit screen
in certain configurations. In order to hide it, we fade it out/in
together with the circular reveal.

Test: manual
Test: atest NotificationQSContainerControllerTest
Test: atest LargeScreenShadeHeaderControllerTest
Test: atest LargeScreenShadeHeaderControllerCombinedTest
Fixes: 244455245
Change-Id: Ie8b8fb07b28e18b9620a948fbb6589394c4224d6