Properly notify expand / collapse state and add better tests

* Previously only notifying if expansion state changed, now
  notify for a bubble being collapsed and expanded (i.e. tapping
  between bubbles)
* Adds a bunch of tests around expansion:
  - Checking different state scenarios for entry listener
  - Verifying BubbleStateChangeListener is called when expected
  - Verifying BubbleExpansionChangeListener is called when expected

Bug: 123567636
Test: atest BubbleControllerTest
Change-Id: I54ec9d9b4fb0b4fb6e741fb80d0f1150e63e26ee