Updates notifications and media visibility during secure lock device

1) Factors secure lock device enabled state into
KeyguardNotificationVisibilityProvider#userSettingsDisallowNotification,
which determines when notifications should be visible on keyguard.
2) Updates NotificationManagerService.StrongAuthTracker#onStrongAuthRequiredChanged
flow to factor in secure lock device enabled state, which updates
userInLockDownModeNext, which is used to cancel notifications when
entering lockdown and posts notifications on exit from lockdown mode
3) Factors secure lock device enabled state changes into
MediaCarouselController visibility

Flag: android.security.secure_lock_device
Bug: 396641431
Bug: 396680098
Bug: 401645997
Fixes: 400307326
Fixes: 400308016
Test: atest KeyguardNotificationVisibilityProviderTest
Test: atest NotificationManagerServiceTest
Test: atest MediaCarouselControllerTest
Change-Id: I099fe3ee8499ef69af2074e2b40fab95114c601a