Transitions - Add ALTERNATE_BOUNCER support

* Add KeyguardState.ALTERNATE_BOUNCER and distinguish this
from the KeyguardState.PRIMARY_BOUNCER
* Remove bouncer state from the KeyguardRepository; instead
rely on the bouncer visibility states from KeyguardBouncerRepository

Bug: 268240415
Test: manually check KeyguardTransitionAuditLogger logs
Test: atest KeyguardInteractorTest KeyguardTransitionScenariosTest
Change-Id: I130647913e5344e76e9e047f619022e7a9f1498e