Change the way nud encryption/locked status is done

[Desrever Nu]

currently it doesn't take into account non-encrypted wallets. :

 if (responseObject.containsKey("unlocked_until")) {
    long lockedUntil = (long) responseObject.get("unlocked_until");
    if (lockedUntil == 0) {
        LOG.warn("Nu client is locked and will not be able to submit liquidity info."
                + "\nUse walletpassphrase <yourpassphrase> 9999999 to unlock it");
    }
}

To know if a wallet is encrypted or not could query nud -unit=B help | grep encrypt and search for : encryptwallet <passphrase>

as suggested by mos