The user can choose to supply an intermediate
certificate through the config, like they can
for the root key. If none is supplied,
the KDS is queried for a valid ASK.
With the introduction of SNP-based attestation on AWS
some of the information in the report (MAAToken) is not
applicable to all attestation reports anymore.
Thus, make verify cmd CSP-agnostic and move
CSP-specific logic to internal/verify.
Also make internal/attestation/snp CSP aware.