Tor should self-test reachability of TCP listeners exposed by PT's

It would be useful if Tor would do self-test of TCP port reachability for bridge listeners and not just the ORPort itself.

Currently when a bridge operator starts their Bridge Relay, Tor will test whether their ORPort is available from the internet, but we do not test the reachability of, for example, the obfs4 TCP port.

We believe that just testing for whether the port is available to the internet is better than to actually test if the port, for example, is able to speak the obfs4 protocol.

We should probably have a way to disable the warning that is emitted if a port is not reachable if, for example, the bridge is actually lying to Tor about its port, does not have a port, or the port is exposed via UDP instead of TCP.