JWT Auth - ML-DSA Support

Per https://datatracker.ietf.org/doc/rfc9964/, support has landed in JWT RFCs for ML-DSA signatures. This might be the final piece of justification we need (cc @DrDaveD) to fork hashicorp/cap and add ML-DSA support there and elsewhere.

We might be blocked on https://github.com/go-jose/go-jose/issues/272 as well, but if/when that lands we can likely move forward with a fork of cap if we need to.