Function run_policy_add_call 

async fn run_policy_add_call(
    key_address: Address,
    root_account: Option<Address>,
    target: Address,
    selector: [u8; 4],
    recipients: Vec<Address>,
    tx_opts: TransactionOpts,
    send_tx: SendTxOpts,
) -> Result<()>

cast keychain policy add-call — merge a selector rule into a target scope.