Assorted dot-wrangling.

- Fixes issue with dots showing up on the wrong side, because code assumed the stack starts on the right when it actually starts on the left now.
- Animates dots out when they're behind the stack/when collapsing from expanded state.
- Animates dots out when expanding.

Remaining issues include: hiding the app badge (deceptively hard), updating state for DND as soon as it changes (vs. when a new bubble is posted, also hard).

Test: manual
Bug: 145245204
Bug: 137213469
Change-Id: I9e2ff29c62ba8c8d0f052e42386b5d517952984e