Updates to KM4.1

This CL adds:

- The IDENTITY_CREDENTIAL_KEY tag.  This new tag is not actually used
  by Keymaster at all.  It's used by the new Identity Credential HAL in
  its key attestations, which use the Keymaster format and the Keymaster
  attestation key.

- A VerificationToken argument to deviceLocked, used for StrongBox
  implementations.

- Some error codes, including one to diagnose unprovisioned
  attestation keys/ids.

- Clarifications in the documentation.

Test: VtsHalKeymasterV41TargetTest
Change-Id: Iae7151e2d9b328dd73e5cd78e59687ef29bab4f0