Update Identity Credential VTS tests.

These updates are based on input/experiences implementing this
HAL. There are no API changes.

 - Specify that the validity for credentialKey certificate shall be
   from current time and expire at the same time as the attestation
   batch certificate.

 - Require challenge passed to getAttestationCertificate() is
   non-empty.

 - Fix bug in VTS tests where the startPersonlization() result was not
   checked.

 - Remove verifyStartPersonalizationZero test since it cannot be
   completed.

 - Ensure secureUserId is non-zero if user authentication is needed.

 - Specify format for signingKeyBlob in generateSigningKeyPair() same
   way we do for credentialData in finishAddingEntries().

 - Modify EndToEndTest to decrypt/unpack credentialData to obtain
   credentialPrivKey and storageKey and do cross-checks on these.

 - Modify EndToEndTest to decrypt/unpack signingKeyBlob to obtain
   signingKeyPriv and check it matches the public key in the returned
   certificate.

 - Add new VTS tests for user and reader authentication.

 - Relax unnecessary requirements about SessionTranscript structure -
   just require it has X and Y of the ephemeral key created earlier.

 - Allow calls in VTS tests to v2 HAL to fail - this should allow
   these VTS tests to pass on a compliant v1 HAL.

Bug: 156911917
Bug: 158107945
Test: atest VtsHalIdentityTargetTest
Test: atest android.security.identity.cts
Merged-In: I11b79dbd57b1830609c70301fea9c99f9e5080cb
Change-Id: I93003389012e69c6df23e1bcebeafde8281caf9c