Updates to bubble drag zones

1. Update the bubble bar drop target to be pill shaped. The drop
   target uses the current size and position of the bubble bar.
2. Update the dismiss drag zone to a circle shape rather than rectangle.
   Also update the position of the X dismiss icon, aligning it with the
   dismiss drag zone.
3. Updates the positioning logic for the DismissView to support bubble bar.

Flag: com.android.wm.shell.enable_bubble_to_fullscreen
Fixes: 404920503
Fixes: 404916611
Test: atest DragZoneFactoryScreenshotTest
Test: atest DragZoneFactoryTest
Test: atest DropTargetManagerTest
Test: manual
       - turn enable_bubble_to_fullscreen flag on
       - drag the bubble bar and an individual bubble through the dismiss zone
       - observe behavior
       - repeat with flag off to verify existing behavior
Change-Id: Ia3d0e680aa55bd96b094d7e4ca523cdb21ae3694