[bc25] Define animated transitions for Dual Shade overlays.

These animated transitions are temporary, and will be replaced by more
 refined animations in the future.

In addition, define the user actions to switch between the notifications
 and quick settings shades.

This CL also removes some obsolete remnants of scene shade transitions.

Bug: 356596436
Flag: com.android.systemui.scene_container
Flag: com.android.systemui.dual_shade
Test: Manually tested by expanding and collapsing the shade over the
 lockscreen and gone scenes, as well as attempting to overscroll.
Change-Id: Iabf1e7b763a94de9032d6f3cebf80ad0baaf2d7b