Bubble overflow - core functionality

BubbleStackView
- create show-overflow-button
- create expanded view to show overflow activity

BubbleOverflowActivity
- add adapter for recycler view of BadgedImageViews
- select bubble to promote it out of overflow, to first bubble in row

BubbleExpandedView
- create overflow intent
- add null bubble checks for overflow expanded view

BubbleData
- new list: overflow bubbles
- only repack bubbles in row (leave overflow order alone)
- update sortKey() to account for last access in addition to last
update. When users select a bubble to promote it out of overflow, it
counts as one access (instead of update); if sortKey does not check last
accessed time, the order is lost in the next repacking and the bubble goes
back to overflow.
- remove oldest bubbles if overflow bubble count > 16

BubbleController
- add callback that updates overflow activity when data changes
- allow overflow activity to set callback
- add/remove bubbles from bubble row ui

BadgedImageView
- set update() param to bubble only
- save other params in Bubble.java so that overflow can update
BadgedImageView with just a bubble

Bug: 138116789
Fixes: 148232991
Fixes: 148232992
Test: (manual) add 5+ bubbles: show-overflow-button shows in bubble row
Test: (manual) tap show-overflow-button: overflow shows aged out bubbles
Test: (manual) remove bubbles, count <= 5: overflow button hides
Test: (manual) tap bubble in overflow: bubble promoted to left of top row
Test: atest SystemUITests

Change-Id: I020ee4c9e16b236043c5cc244e610725e86bcc37