Update BubblePositioner to have some things for bubble bar

- whether bubbles are showing in the bubble bar
- whether bubbles are showing on launcher home in the bubble bar
- the size of the bubble bar (needs to be in sync with launcher)
- the sizing for the expanded view when bubbles are in the bubble bar

Currently everything is unused but will be used in future CLs.

Test: treehugger
Bug: 253318833
Change-Id: I33240a61548d20e7052bdba3badb7dc79987a8de