Add fallback handling for gesture nav mode switch and launcher destroyed mid-gesture

If the gesture nav mode switches to button nav mode mid gesture, specifically while a recents animation start is pending, then we never invalidate AbsSwipeUpHandler. This leaves the LauncherInitListener registered in the ActivityTracker until the AbsSwipeUpHandler is invalidated by something like a quick switch. Since the AbsSwipeUpHandler is not invalidated by pressing the home button, this leaves the home button seeming unresponsive.

Also added some clean up logic and debug logging to AbsSwipeUpHandler.onTasksAppeared since this path was confusing this investigation.

Flag: NONE code clean up, debug logs and bug fix
Fixes: 340748907
Test: adb shell cmd overlay enable-exclusive --category com.android.internal.systemui.navbar.threebutton && adb shell am start -n <component> while mid-gesture
Change-Id: I72f0656a2a2b92006d2d13ba5868062f2f0aec33