Function setup_zk_verifier 

pub fn setup_zk_verifier<H>(
    cs: ConstraintSystem,
    log_inv_rate: usize,
) -> Result<ZKVerifier<H>>
where
    H: ParallelHashSuite + Clone,
    Output<H::LeafHash>: SerializeBytes + DeserializeBytes,

Set up only the ZK verifier (no prover) for the given constraint system using H as the Merkle hash suite. Cheaper than setup_zk when proving is not needed.