6/n: Have FaceService extend BiometricService

In the Service layer, this change is pretty much the same as ag/4340638.
FingerprintService already extends BiometricService which contains all
of the common code. FaceService now does the same after this change.

Updated the Manager layer to use the infrastructure added in P, namely
  - Private APIs for BiometricPrompt
  - Removed FaceManager#CryptoObject, use biometrics/CryptoObject directly
  - Few other BiometricAuthenticator things

Bug: 110387294

Test: enrolling FP still works
Test: removing FP still works
Test: changing FP name persists across reboots
Test: enumerating still works (extra framework fp, extra hw fp)
Test: keyguard still receives lockout reset callbacks

Change-Id: I2195b08e28d024a120df56fe87b0dd4f9b96505a