Create a user type that contains ML-DSA and ML-KEM,

[andrea-dintino]

Right now, only the "issuer" type contains only Dilithium.

We need a generic user that contains ML-DSA and ML-KEM, which could be a clone of the current issuer, we can call it something like "extended-user" or "xt-user" or "pqc-user"

[matteo-cristino]

The type of key present in the DID document is choosen in the client side, no modification is required in here