Add face auth triggers in FaceAuthInteractor

Summary of changes:
 - Renames KeyguardFaceAuthInteractor to SystemUIKeyguardFaceAuthInteractor
 - Extracts public API from the interactor as the new interface KeyguardFaceAuthInteractor
 - Provides a no-op implementation of the interactor that can be used in SystemUI variants that don't support face authentication

Context:
 - Injecting the interactor in UdfpsController and KeyguardSecurityContainerController causes the build to break for other SystemUI variants
   as they depend on these components but don't have KeyguardFaceAuthModule installed.
 - Having a no-op interactor lets us avoid having to introduce dependency on the new face auth system when it is not required.

Bug: 262838215
Test: verified trigger manually
Test: atest UdfpsControllerTest
Change-Id: Ie57ea4b965cac24d99cb66d9acbffce590c2ff51