Vertical bubbles in landscape

- in landscape the bubbles now show on left/right side & layout vertically
  instead of remaining at the top and being horizontal
- introduces BubblePositioner to track the config changes and available
  screen rect for bubbles based on insets / cutouts
- pointer can now go left or right
- fixes issue where overflow could be past screen height in landscape

Test: manual - bubbles at the top in portrait, bubbles on left / right side
               in landscape, bubbles at the top with notch, bubbles on left
               / right side in landscape with notch, with/without gesture nav
Bug: 167413172
Change-Id: I4528035fd03d17d11865ddcdddc4732f5a8e616a