Treat changes in device-state as user-activity.

PowerManager will now treat changes in the device state from
DeviceStateManager as user-activity for the purposes of calculating
idle timeouts.

Bug: 199993642
Test: Check logs to verify that user-activity is updated when
      changing device states.
Test: atest PowerManagerServiceMockingTest
Change-Id: Ib5e543dd502d6b9b8ef1fef7e1b0f8a188f3cf1e