SystemUI: tuner: navbar tuner refresh

* Expose all AOSP keys to UI
* Load proper default for 2button/gesture nav
* Reset tuner key on nav mode change (support gesture nav)
* Bring back custom keycode, bug fixes
* Support dynamic height change (gesture nav extra buttons)
* Support menu button on gesture nav by default
* Support cursor key on gesture if IME nav rendering is off
* Do NOT load custom layout if IME nav rendering is on + gesture on

Change-Id: I1332e0e9d7f49cbc5c12c47e566b3c849c6c250b