Prepare BubbleBarViewController to support persistent task bar.

Added required resources for the transient taskbar. Unified
BubbleBarViewController logic for the persistent taskbar.

Bug: 350065038
Flag: com.android.wm.shell.enable_bubble_bar
Test: atest
Change-Id: I24e6d2d43bf8145cdcc71c75da0cb6f6e84373da
2 files changed