framework: move device key handler logic, fix gesture camera launch

In order to make device camera gestures behave the same way as launching
the camera by double tapping the power button, route DeviceKeyHandler
logic through the GestureLauncherService.

A callback is used in order to avoid publishing the
GestureLauncherService into the System service registry, because the
KeyHandler code cannot directly access services local to the system
process.

OPO-427

Change-Id: I2a8860b278f65ccf31bfee151513d8a23ab746c5
Signed-off-by: Roman Birg <roman@cyngn.com>

KeyHandler: don't break old interfaces

Causing bootloops on devices, don't break old interfaces in the
framework.

OPO-427

Change-Id: I49473b057bc4ed4710e9092c76e41c6a8134d2de
Signed-off-by: Roman Birg <roman@cyngn.com>

SystemUI: handle camera launch gesture from keyhadler

Includes partial reverts:

    Revert "KeyHandler: don't break old interfaces"
    This reverts commit 31ecbdc5.

    Revert "framework: move device key handler logic, fix gesture camera launch"
    This reverts commit db1b4e6e.

Ref: OPO-427

Change-Id: Ic15543a8f63ad4521ab0ab536d00224b0bd70f8c
Signed-off-by: Roman Birg <roman@cyngn.com>