[cryptotest] Pull NIST AES-GCM test vectors

[sadmansakib-git]

This PR pulls in the NIST testvectors for AES-GCM, and includes the associated parser and JSON schema. The file format of the test vectors are different than the ones that we have seen so far and can not be parsed with the existing parse_rsp() method from cryptotest_util.py. Created another parse_gcm_rsp() to parse AES-GCM test vectors.