Function verify_nitro_attestation

pub fn verify_nitro_attestation(
    signature: &[u8],
    signed_message: &[u8],
    payload: &AttestationDocument,
    timestamp: u64,
) -> SuiResult<()>

Given the signature bytes, signed message and parsed payload, verify everything according to https://docs.aws.amazon.com/enclaves/latest/user/verify-root.html and https://github.com/aws/aws-nitro-enclaves-nsm-api/blob/main/docs/attestation_process.md.