Add a verification flow for the user to exit repair mode

Create a special user id USER_REPAIR_MODE and an intent
ACTION_CONFIRM_REPAIR_MODE_DEVICE_CREDENTIAL for the repair
mode client triggering a exiting repair mode verification flow
that verifies credentials the user enrolled in normal mode.
Functions in LockSettings are updated to handle the new
user id. Information needed to verify the repair mode user is
retrieved from the repair mode file when the verifyCredential
api is called.

Bug: 277561275
Test: atest com.android.server.locksettings
Test: am start -a android.app.action.PREPARE_REPAIR_MODE_DEVICE_CREDENTIAL
      settings put global repair_mode_active 1
      am start -a android.app.action.CONFIRM_REPAIR_MODE_DEVICE_CREDENTIAL
      The credential is verified successfully.
Change-Id: I51699d157e9de1a57bc36797ea005bcdd51aadb3
Merged-In: I51699d157e9de1a57bc36797ea005bcdd51aadb3