Draft: Priority-based queueing for StreamMap

Obsoletes !2092 (closed)

crates/tor-proto/src/circuit/streammap/priority_map.rs

@@ -110,11 +110,9 @@ where
             }),
         }
     }
-    // XXX: maybe this should be sorted
     fn iter(&'a self) -> Self::Iter {
         self.m.iter()
     }
-    // XXX: maybe this should be sorted
     fn iter_mut(&'a mut self) -> Self::IterMut {
         self.m.iter_mut()
     }