Add dock_info_bottom_area_overlay

Add and overlay near keyguard_bottom_are to host the promo animation.

Bug: 182220090
Bug: 178998477
Test: atest SystemUITests:KeyguardBottomAreaTest
Test: atestSystemUITests:DockIndicationControllerTest
Change-Id: I93a3ddee3f4dc3273ba446dab6f9df49c262e955