Single source of truth for auth state

Merging UnlockMethodCache and KeyguardMonitor into KeyguardStateController,
making it injectable and introducing KeyguardStateController#isUnlocked
in order to make it easier to keep track of the lock screen state.

Test: atest SystemUiTests
Test: unlock with face, lock again
Test: unlock with password, lock again
Bug: 139363827
Change-Id: I37ac8c7826101852c61382559be9868125c15fac