Intercept power key events during a panic gesture

While the user completes the panic gesture (5 presses) we should
intercept power key events (presses 3,4,5) to avoid triggering
the lock screen events (<- better descriptor?).

I am proposing that we should continue to intercept the button presses
after the panic flow has triggered because of possibility of hitting the
button more than five times because:
- Device is in their pocket
- User is in distress and shouldn't have time the 5th press

Bug: 170133395
Test: atest GestureLauncherServiceTest
Change-Id: I89619a748c5dc1886f5c27e49780030fcbdb61ad