Continuously clip notifications according to their sibblings

Notifications now avoid overlapping each other by clipping its
background and content if they overlap. In particular with
physics based animations as well as the row transparency this
was particularly visible, but it could also happen previously

Fixes: 403531742
Flag: com.android.systemui.physical_notification_movement
Test: atest SystemUITests
Change-Id: I1dfd57fce521635218300de6ed015e92fc84b9fc