Don't accept connections until the Tor connection completes (stretch goal)

Currently, we always accept incoming TCP connections, and we then have to reset them if the outgoing connection fails. This sucks.

Working around this is going to be quite hard, since it'll require some major rearchitecting of the way we hook around smoltcp. I think it's worth doing given we've gotten most of the other base functionality done though, as it should remove a whole load of jank from the experience.