Function get_named_object_grants 

async fn get_named_object_grants(
    client: &Client,
    catalog_table: &str,
    name: &str,
) -> Result<Vec<ObjectGrant>, ConnectionError>

Get privilege grants on a named infrastructure object (cluster, network policy).

catalog_table is the system catalog table (e.g., "mz_clusters", "mz_network_policies"). Returns (grantee, privilege_type) pairs from mz_aclexplode, filtering out system roles.