Stop tracking bubble bar bounds and only listen for top coordinate

Shell needs the top coordinate of bubble bar to see where to place the
bottom edge of the expanded view.
The left and right value of the bounds were used for the collapse/expand
animation of the expanded view. But we already know the location of the
bubble bar. Updating the expanded view animation to scale in from the
right edge of the screen. And not the center of the bubble bar view
itself.
Reduces the number of calls needed from launcher to shell to update the
bounds as they change every time number of bubbles changes or bar itself
expands/collapses.
Simplifies syncing between launcher and shell as we no longer need to
keep the entire bounds in sync. Just the top coordinate of the bar which
changes when user is on home screen or in the app.

Bug: 330585402
Flag: com.android.wm.shell.enable_bubble_bar
Test: atest BubblesTest
Test: atest WMShellMultivalentTestsOnDevice
Test: atest WMShellRobolectricTests
Test: bubble bar drag
  - drag bar from right to left
  - expand the bar
  - check that expanded view scales in from left edge
  - collapse and drag bar back, check the animation
Test: selected bubble drag
  - drag expanded bubble from right to left
  - check that expanded view scales in from the left edge
  - drag the bubble back to right, check animation
Test: other bubble drag
  - drag a unselected bubble from right to left
  - check that the selected bubble expands in from left edge
  - drag the bubble back to right, check animation again
Test: drag bubble from right to left, observe that expanded view
  expand animation originates from the bubble bar
Change-Id: Ica786e6116e75db9366653cf9e66746909761696