Animate the bubble bar for the first bubble

This change animates the bubble bar for the first bubble.
When we're in home -- the bubble bar bounces in and stays visible
When we're in app -- the bubble bar bounces in, then animates to
the stashed handle.
When the bubble bar auto expands, we currently animate the bubble
bar already expanded. In the future we'll time the expansion
until after the bubble bar settles in.

Demo: http://recall/-/bJtug1HhvXkkeA4MQvIaiP/hIGwtb3YKyCT9Ke9adZNgY

Flag: ACONFIG com.android.wm.shell.enable_bubble_bar DEVELOPMENT
Bug: 339066271
Test: atest BubbleBarViewAnimatorTest
Change-Id: I80ce55676b72a50bab23623e0b5c1e602690682f