Align the bubble bar with the taskbar in overview and app

Whenever the bubble bar is unstashed and taskbar is present, the
translationY of the bubble bar is now adjusted so that it is aligned
with the taskbar.

Demo: http://recall/-/bJtug1HhvXkkeA4MQvIaiP/e3dlacSsSebQfEFTEt10JM

Fixes: 286247080
Test: Manual:
      - Add bubbles to the bubble bar.
      - On home observe the bar is aligned with hotseat
      - Switch to overview and observe the bar is aligned with taskbar
      - Go back to home. Bar aligns with hotseat.
      - Launch an app. Swipe up to load taskbar. Bar is aligned with taskbar.
      - Go back to home. Bar aligns with hotseat.
Change-Id: I93c2232d4862be4c97e36ddb6c9d680b01e555ad