Function sign_commitment 

pub fn sign_commitment(
    commitment: &[u8; 32],
    signing_key_seed: &[u8; 32],
    key_id: impl Into<String>,
    attester_id: impl Into<String>,
    issued_at: impl Into<String>,
) -> ProvenanceAttestation

Sign an arbitrary commitment (a frame commitment or a Merkle root).