Bubble bar dismiss

* Added additional methods to `IBubbles` protocol in order to communicate bubble dismissal to the WMShell.
* Added animation cancellation if the expanded state changes in the middle of animation.
* Implemented bubble dismiss functionality in `BubbleController`

Bug: 271466616
Test: manual, TBD
Flag: WM_BUBBLE_BAR
Change-Id: Iaf3de681d425adb1ff6270ff4a380c6b59abc6c2