Bubble bar drag to dismiss

* Added dismiss view to the taskbar
* Bubble drag to dismiss of:
  * A single bubble when the bubble bar stack is expanded
  * All bubbles when the bubble bar stack is colapsed
* Added dismiss related calls to WMShell in SystemUI through SystemUIProxy

Bug: 271466616
Test: manual, TBD
Flag: WM_BUBBLE_BAR
Change-Id: Ibb62a0b1ab9fafa8a3acf07450ce2132ed605adc