Re: [sr-dev] [kamailio/kamailio] nats: Add publish function (PR #2915)

re-updated PR to add callbacks to publisher connections; right now the publisher callbacks are the same as the subscriber callbacks.

Thus, kamailio nats module can make use of nats lib reconnection(e.g. natsOptions_SetRetryOnFailedConnect() function) and not implement a reconnect mechanism by itself.

I will later make a new PR to make the parameters that control nats lib reconnect mechanism, configurable: ``` natsOptions_SetMaxReconnect(opts, 10000); // how many times nats lib tries to reconnect before giving up; -1 is forever if i'm not wrong natsOptions_SetReconnectWait(opts, 2 * 1000); // the interval between reconnect retries ```

Thanks, Stefan