Fix race between invalidateInput and restartInput

Since ZeroJankProxy, we allowed startInput to be asynchronous, which
allows two conflicting operations of #invalidateInput and #restartInput
to race with each other.
In order to fix the race, invalidateInput could fallback to calling
restartInput() if there is an ongoing restartInput.

Bug: 396066692
Test: atest InputConnectionLifecycleTest
Flag: android.view.inputmethod.invalidate_input_calls_restart

Change-Id: Id87a6165fa9eda6d328165e9a6ba88ca56bea610