circuit-v1.2.0: add support for AIP-108 and for nested JSON

First, we add support for federated & audless accounts. See https://github.com/aptos-foundation/AIPs/blob/5bb1483a9344cff56fc48c790f2c1394428eadb0/aips/aip-108.md for details. Second, we now recognize the depth that potentially-sensitive fields are at in the JSON (e.g., sub or aud). This is because some OIDC providers may allow users to insert their own sub-fields in the JWT. See #35 for the implementation.