Add control port trace logging to tor

To diagnose #30235 (closed), we need to be able to see what tor is sending and receiving on the control port.

I don't think that tor has any logging code for control port messages: I had a quick look, and there wasn't anything obvious.

Showing each message at info level could be good, but it might also be risky? Maybe we should safe_string_client() the actual message text.

nickm and catalyst are refactoring the controller code right now, so they might know where I should add the logging statements.