Fix an edge case of IME surface overlapped on the overview

A race condition might happen when a IME layering overlay target visible
unexpectedly during swiping the app task to the overview, that causes
InputMonitor didn't call hideCurrentInputMethod when the input focus
change since isImeAttachedToApp still return true in that time, but
acutally it will become false after the IME layering overlay became
visible.

Refine the logic to keep tracking isImeAttachedToApp and IME visible
state during the swiping up gesture, and hide IME when the IME is
visible and not attachable on the new target.

Fix: 222064495
Test: manual as test steps:
   1) install a 3rd-party app "Always visible volume button"
   2) enabling "Display over the other apps" for 1) to show the volume
      button
   3) launching any apps with showing IME
   4) swping up to the overview screen, verify if IME hides expectedly
   5) repeat 3-5 10 times, expect no IME being overlapped on the
      overview screen, and the task snapshot didn't show the IME
      snapshot after hiding the IME.
Change-Id: I71f397b93b9f94e9351ded8191676b1dfb249d9e