Merge "Expose `FaceManager` APIs as `@SystemApi`." into main

core/api/system-current.txt

core/java/android/content/Context.java

core/java/android/hardware/biometrics/flags.aconfig

core/java/android/hardware/face/FaceManager.java

core/java/android/hardware/face/IFaceService.aidl

core/res/AndroidManifest.xml

.../coretests/src/android/hardware/face/FaceManagerTest.java

data/etc/privapp-permissions-platform.xml

packages/Shell/AndroidManifest.xml

...m/android/server/biometrics/sensors/face/FaceService.java

services/tests/servicestests/AndroidManifest.xml

...droid/server/biometrics/sensors/face/FaceServiceTest.java