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

base(_base),
    target(_target), conn(base), reconnect(true), reconnect_ev(0),
    reconnect_timeout(RECONNECT_TIMEOUT_START)
{
    reconnect_ev = event_new(base, -1, 0, reconnect_cb, this);
    if (!reconnect_ev)
        LogPrintf("tor: Failed to create event for reconnection: out of memory?\n");
    
    if (!conn.Connect(_target, std::bind(&TorController::connected_cb, this, std::placeholders::_1),
         std::bind(&TorController::disconnected_cb, this, std::placeholders::_1) )) {
        LogPrintf("tor: Initiating connection to Tor control port %s failed\n", _target);
    }
    
    std::pair<bool,std::string> pkf = ReadBinaryFile(GetPrivateKeyFile());
    if (pkf.first) {
        LogPrint(BCLog::TOR, "tor: Reading cached private key from %s\n", GetPrivateKeyFile().string());
        private_key = pkf.second;
    }
}
TorController::~TorController()
{
    if (reconnect_ev) {
        event_free(reconnect_ev);
        reconnect_ev = nullptr;
    }
    if (service.IsValid()) {
        RemoveLocal(service);
    }
}
void TorController::add_onion_cb(TorControlConnection& _conn, const TorControlReply& reply)