Keeps power key intercepted during a panic gesture

The GestureLauncherService is used to detect camera and sos emergency
gesture by multi-pressing power, if it intercept power key, we should
return the intercept state that could prevent the following detector
processing the power key cause unexpected single tap.

Bug: 194522413
Test: keep pressing power to see if screen would turn off.
Test: atest GestureLauncherServiceTest
Change-Id: I3db7390df720f24f9b312946b1d8e01d672e6ef3