Fix arrow animation when the new bubble added and old bubble removed.

The AddingAndRemoving animation now uses a newly selected bubble index
and added bubble index arguments.

Test: BubbleAnimatorTest
Test: Manual. Enable optional overflow bubble.
Create a bubble bar with overflow containing a single
bubble. Open the overflow menu and click an overflow bubble icon.
Observe that a new bubble is added and immediately expands while the
overflow bubble is collapsing. Observe that the arrow animates to the
new bubble's position.
Test: Manual. Have few bubbles in the bubble bar. Collapse any bubble.
Observe arrow animated correctly to the newly selected bubble position.
Flag: com.android.wm.shell.enable_bubble_bar
Bug: 359952121

Change-Id: I8321e2f532189e7599b029083199e034e38080e3