Add logic to the drag DragLayout to detect bubble bar drag events.

Introduced new logic to the DragLayout to detect when application icon
is being dragged and dropped over the bubble bar drop target zones.

Bug: 388894910
Flag: com.android.wm.shell.enable_create_any_bubble
Test: DragAndDropControllerTest
Test: Manual. Drag app icon from the task bar while inside the
application. Observe the split-screen disappearing when dragging to the
Bubble Bar drop zones. Drop icon to the Bubble Bar drop zone. Observe
the task bar is hidden.
video: http://recall/-/gx8ASgewUeUS3QYohfrd1J/eDvhe19PvyOveHLbzqQlNw

Change-Id: I6dae093c7ddd9963c990e5533dbf854f82ce850e