Call reportFailedPasswordAttempt from Work Challenge

Entering the wrong credential in ConfirmDeviceCredentials should
also count as failed attempts for the password, after which the
DPC have set a restriction to wipe the work profile.

Fixed related issues, such as the CredentialChecker re-sending
the result after onResume causing additional attempts to be counted.

The new error message String is also displayed initially when there
are pending attempts to inform the user that they are not starting
from fresh.

Bug: 26677759
Change-Id: I70cfae4c05e705ad7fe93bc071426459b79e7d0c