Use a reveal animator for bubble icons (2/n)

Use a similar animation for bubble bar icons as we use for taskbar. When
stashing or unstashing, use a reveal animator to show the icons.
Previously we were scaling the icons to the desired size.
New reveal animator matches what is used for taskbar.

Bug: 345488489
Test: TransientBubbleStashControllerTest
Test: stash and unstash bubble bar in app by swiping up from taskbar
Test: expand and collapse bubble bar in app by swiping up on bar
Test: expand and collapse bubble bar on home screen by tapping on it

Flag: com.android.wm.shell.enable_bubble_bar
Change-Id: I24b0c64673d6becfa2ed68993bb95fe78e105670