Force showing navigation bar while IME is visible

This CL revokes navigation bar control to make navigation bar visible
while IME is showing, so the button to dismiss IME would be available.

This CL also lets IME receive visible navigation bar insets, regardless
of the navigation bar visibility.

Fix: 167971834
Fix: 186789472
Test: atest WindowStateTests WindowInsetsControllerTests
Change-Id: I2e723d4fc50d006127caa473d67c2f6af0d2cbcd