chore(worker): introduce an abstraction for streaming-based publish workers

Some things doesn't need to receive data, just to push!

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

ofborg/src/worker.rs

@@ -1,5 +1,6 @@
 use std::marker::Send;
 
+use futures::Stream;
 use serde::Serialize;
 
 pub struct Response {}
@@ -68,3 +69,7 @@ pub trait SimpleWorker: Send {
         body: &[u8],
     ) -> Result<Self::J, String>;
 }
+
+pub trait StreamWorker: Send {
+    fn publisher(&mut self, chan: &mut lapin::Channel) -> impl Stream<Item = Box<QueueMsg>>;
+}