Introduce SingleKeyGestureDetector to PhoneWindowManager

The SingleKeyGestureDetector is used to detect the single key gesture
such as short press, long press or multi presses.

If the key has been handled by other policy, it should call 'reset'
to reset all gesture states.

This patch also refactor the power key and back key if the long press
behavior is enabled.

The detector can detect below gestures:
- single press
- long press
- very long press
- multiple presses (press count > 1)

Bug: 169058831
Bug: 127687575
Test: atest KeyEventTest SingleKeyGestureTests
Test: atest GlobalActionsImeTest PowerButtonTest
Test: manual (short press power, long press power, double tap power)
Change-Id: I28ff4373ba57b16e580b8eaaca26a3fa81770d0f