Restore the last IME visiblity of the app window when allowed

Since when bring an existing app task to foreground or quick switching
app task with gesture navigation will first see the task snapshot
during app transition,

If the task previously focused and shown IME, even the task may hide
IME when switching to the next task, As the goal of
go/ime-transition-improve-s mentioned, if the task is still focused by
editor, we should keep the original focused IME shown and keep
the input connection focused state when navigating back to the
original task.

Bug: 166736352
Test: atest CtsInputMethodTestcases
Test: manual by focusing app with an editor to show keyboard,
      switch the app task to the next with gesture nav and then
      switched back, expected the soft-keyboard is still shown.

Change-Id: I63b144bed6c37569d79fba1c2b63dd4f1074f0f6