Turn off dream back gesture and gesture handling when biometric prompt is showing

We disable back gesture on dreams but this prevents users from exiting
the biometric prompt when triggered by a dream. Our vertical swipe
gesture interception also prevents the user from entering a pattern
as the shade/lockscreen are triggered instead.

This change turns off these features when the biometric prompt is
showing.

Bug: 391193603
Bug: 413511537
Fixes: 391193603
Fixes: 413511537
Test: atest DreamOverlayServiceTest
      (see 413511537 for video with fix)
Flag: com.android.systemui.dream_biometric_prompt_fixes
Change-Id: I0de859f5ed7a335bba36c677645c8998177a23bf