Ensure controller RESOLVE commands respect __LeaveStreamsUnattached

Ensure controller RESOLVE commands respect __LeaveStreamsUnattached

https://trac.torproject.org/projects/tor/ticket/1525

"The codepath taken by the control port "RESOLVE" command to create a
synthetic SOCKS resolve request isn't the same as the path taken by
a real SOCKS request from 'tor-resolve'.
This prevents controllers who set LeaveStreamsUnattached=1 from
being able to attach RESOLVE streams to circuits of their choosing."

Create a new function connection_ap_rewrite_and_attach_if_allowed()
and call that when Tor needs to attach a stream to a circuit but
needs to know if the controller permits it.

No tests added.