Launch FingerprintSettings directly when user clicks "Fingerprint
Unlock". Let Fingerprint settings peform confirmLock() or chooseLock().
And to have smoothly animation, instead of generating challenge in
FingerprintSettings::onActivityResult(), challenge is generated in next
visible activity, and pass it back through next activity result.
Bug: 197717071
Test: atest GatekeeperPasswordProviderTest CredentialModelTest
Test: atest AutoCredentialViewModelTest FingerprintStatusUtilsTest
Test: RunSettingsRoboTests2 FingerprintEnrollIntroductionTest
Test: Manually test fingerprint enroll in settings or suw
Change-Id: Ie27c3c493ea475f6b53cb6bb3f2d45d555f47cb3
160661dc6d