Show IME switcher only when physical keyboard is connected in 3 button nav...

Show IME switcher only when physical keyboard is connected in 3 button nav (instead of also when virtual keyboard is visible)

Bug: 226489759
Test: connect to a physical keyboard in 3 button nav and make sure the ime switcher shows; and doesn't show with virtual keyboard
Change-Id: Ib9a5880eb1bd6d5b877a9f3789ce858f399c4910