Enable onion services using draft arti support

crates/onion-tunnel/src/proxy.rs

 use crate::accounting::BandwidthCounter;
+use arti_client::config::BoolOrAuto;
 use arti_client::TorClient;
 use arti_client::{CountryCode, TorAddr};
 use arti_client::{DangerouslyIntoTorAddr, StreamPrefs};
@@ -215,6 +216,8 @@ where
             stream_prefs.exit_country(cc);
         }
 
+        stream_prefs.connect_to_onion_services(BoolOrAuto::Explicit(true));
+
         let arti_stream = match self
             .arti
             .connect_with_prefs(tor_addr.clone(), &stream_prefs)