Add KATs

[ounsworth]

For Composite KEM, we should follow exactly the ACVP test vector format, which can be found here:

https://github.com/usnistgov/ACVP-Server/blob/master/gen-val/json-files/ML-KEM-keyGen-FIPS203/expectedResults.json
https://github.com/usnistgov/ACVP-Server/blob/master/gen-val/json-files/ML-KEM-encapDecap-FIPS203/expectedResults.json

That would mean that for each composite, we include a JSON blob like:

 "tests": [
        {
          "tcId": "id-MLKEM768-RSA2048",
          "ek": "A1B2C3...",
          "dk": "3CB2A1...",
          "c": "5A9B...",
          "k": "F91B8C7477A6005992EE947BB365EBF1CFE15688BD25DEEFAD54F90922B4B84C"
        },
}