tor-hsservice: use shared status_tx to report OnionServiceStatus via...

Without this patch we only ever receive the initial Shutdown status. Appears to be some remaining fallout from the fix to #1083 (closed). With this patch we now receive Shutdown, a ton of Bootstrapping, an occasional Degraded and finally Running events. With this patch (and !2077 (merged)) I've now successfully launched an onion service and connected to it from separate in-process arti-clients!