Set the default state of canFaceAuth run to false.

This was incorrectly set to true, after a reboot we try to run face auth before there is enough time to update this flow to false

Other changes:
  - Change face sensor to a state flow in FacePropertyRepository
  - Yield after resuming face auth for the user switching scenario. This ensures face auth repository processes the user switch before we trigger face auth.
  - Dont fallback to detect in scenarios where we are already on the bouncer
  - Run the gating checks coroutines on the main dispatcher
  - Update the lockout state of face auth right after user switch.
  - Remove userSwitchingInProgress from UserRepository and replace usages with selectedUser

Fixes: 296611182
Fixes: 285516490
Test: atest DeviceEntryFaceAuthRepositoryTest
Test: atest FacePropertyRepositoryTest
Test: atest KeyguardFaceAuthInteractorTest
Test: verified manually, restart the device, look at the logs to see if face auth is triggered
Change-Id: Ib17f8450b3c11f808551f2b1a8e24ee30d404eeb