IME to systemui

Re-route ime-control to SystemUI when it isn't driven by an app.

This allows multi-window system-ui components to synchronize
with the ime (eg. adjusting for split-screen).

Ime control goes through a new interface IDisplayWindowInsetsController.
This gets set on WM and there is only 1 per display. All of this
is currently handled in DisplayImeController which will also
drive the animation of the IME and dispatch to ImePositionProcessors.

On the server-side, InputMethodControlTarget is separated from
InputMethodTarget so that IME can be controlled by a different
client than the IME target.

Bug: 133381284
Test: Existing IME tests pass
Change-Id: I8e8ed2e09c45998c228df72e52a671fa327308f2