Proofs `alg` verification

[dtsiflit]

For JWT Proofs spec mentions the following:

If Credential Issuer metadata is provided, the alg JWT header of the key proof, and if present, the alg JOSE headers of both key_attestation and trust_chain, MUST match one of the values listed in the proof_signing_alg_values_supported metadata parameter.

Also same for attestation proof

If Credential Issuer metadata is provided, the value of the alg JWT header of the key attestation MUST match one of the entries in the proof_signing_alg_values_supported metadata parameter.

• Validate algorithm for JWT and attestation proofs as specified above.