Have bubble bar unstash gesture track finger

Follow the taskbar motion for unstashing via gesture.
When swiping up in the handle area, move the handle slightly up with the
finger movement.
Once reaching a certain threshold, unstash the bubble bar.
If user swipes up past a certain other threshold, and lifts the finger,
expand the bubble bar. Otherwise leave bubble bar in collapsed state.

Only stashed handle or collapsed bar can be swiped up on.

Bug: 325673340
Test: atest NexusLauncherTests:com.android.launcher3.taskbar.bubbles.BubbleBarSwipeControllerTest
Test: swipe up on stashed handle
Test: tap on stashed handle
Test: enable 3 button nav and tap on bubble bar
Flag: com.android.wm.shell.enable_bubble_bar
Change-Id: I6bb3c201cd03f05e2be55ebb0c972c577373ea79