3/n: Add FaceDialogView and "confirmation" plumbing

This change adds plumbing from <Biometric>Service to SystemUI for requiring
user confirmation (or not). This change also fixes some layout bugs
that were hard to notice.

Bug: 111461540
Fixes: 113130114
Fixes: 116135579

Test: With confirmation, crypto operation does not work until token
      is added to Keystore
Test: Without confirmation, crypto operation works when biometric is
      authenticated
Test: BiometricPromptDemo works, UI elements are all correct
Test: Talkback messages are correct

Change-Id: I2c05577699a29c09777cae4db6c7334c1e6bc179