To be able to label incoming tor connections as different from normal localhost connections in e.g. `getpeerinfo` and the peers list in the GUI it'd be useful to have them connect on an alternative local-only port. Or even better, a UNIX socket.

For manually set-up hidden services this would have to be configured manually and could add a `hsport` option or such. The external port would still appear as `XXXXXXXXX.onion:8333`, however internally it would redirect to a that port.

In the case of `torcontrol` this would be easy to set up automatically. It could add a new (localhost) binding port automatically and this code would have to be changed:
- https://github.com/bitcoin/bitcoin/blob/master/src/torcontrol.cpp#L441
- https://github.com/bitcoin/bitcoin/blob/master/src/torcontrol.cpp#L477

{
    if (reply.code == 250) {
        LogPrint(BCLog::TOR, "tor: ADD_ONION successful\n");
        for (const std::string &s : reply.lines) {
            std::map<std::string,std::string> m = ParseTorReplyMapping(s);
            std::map<std::string,std::string>::iterator i;
            if ((i = m.find("ServiceID")) != m.end())
                service_id = i->second;
            if ((i = m.find("PrivateKey")) != m.end())
                private_key = i->second;
        }
        if (service_id.empty()) {
            LogPrintf("tor: Error parsing ADD_ONION parameters:\n");
            for (const std::string &s : reply.lines) {
                LogPrintf("    %s\n", SanitizeString(s));
            }
            return;
        }
        service = LookupNumeric(std::string(service_id+".onion"), Params().GetDefaultPort());
        LogPrintf("tor: Got service ID %s, advertising service %s\n", service_id, service.ToString());
        if (WriteBinaryFile(GetPrivateKeyFile(), private_key)) {
            LogPrint(BCLog::TOR, "tor: Cached service private key to %s\n", GetPrivateKeyFile().string());
        } else {