Create BubbleViewCallback for the bubble bar and use it

* Creates a separate BubbleViewCallback for use when bubbles are
  showing in the bubble bar. When bubbles are in the bubble bar we
  use a different set of views, so this callback sends the updates
  to those views (BubbleBarLayerView).

* BubbleBarLayerView only deals with the expanded state for bubbles
  so only updates relevant to the expanded state get sent to it.

Test: treehugger / manual with other CLs
Bug: 253318833
Change-Id: Ie68f7538820993680a1cce6a6f782b622fcebbd0