Link InsetsController to IME (IME transitons 4/n)

With this change, InsetsController.show/hide now links to IME. This also
takes care of animating IME along with other types.
Insets API are reactive i.e. they remain in sync with state of IME.

Test: atest InsetsControllerTest
Test: atest ImeInsetsConsumerTest
Bug: 118118435

Change-Id: Ib3997487bd19351d1d23bc70173fc9bdfd23a704