Synchronize bar expansion with WM Shell

When a bubble is added and requested to be expanded, notify WM Shell
to show the expanded view when expansion actually starts on the
launcher side.

Demo: http://recall/-/bJtug1HhvXkkeA4MQvIaiP/cPZuf3STUqX9uFZ4zneRO2

Flag: com.android.wm.shell.enable_bubble_bar
Fixes: 339683389
Test: atest BubbleBarViewAnimatorTest
Change-Id: I0ba27acf8bae560a10b754241f8f2d8e3281cef9