16/n: Add PIN/Password

Bug: 140127687

Make AuthCredentialView abstract, and have the following subclasses
 1) AuthCredentialPatternView
 2) AuthCredentialPasswordView

Back button cancels password authentication

Test: manual test with pattern, pin, password
Test: atest com.android.systemui.biometrics

Change-Id: I95e42144616a59827da25d10d063990452714f76
9 files changed