Intruduce KeyCombinationManager to PhoneWindowManager

Move two keys combination from PhoneWindowManager to
KeyCombinationManager.

- Extract power/volume_down, power/volume_up volume_down/volume_up
  combinations from interceptKeyBeforeQueueing to KeyCombinationManager.
- Extract back/dpad_down, back/dpad_center combinations for tv device.

Bug: 169058831
Bug: 127687575
Test: atest KeyEventTest
Test: atest KeyCombinationTests
Test: manual, (volume_down+power) (volume_down+volume_up)
      (volume_up+power) (back+dpad_down) (back+dpad_center)
Change-Id: Ice2ffa7d6b5418cb50849180bf9b782408e7cb1c