Make route_handler and chan_handler Option<>al in MessageHandler

We currently "support" not having a router or channel in memory by
forcing users to implement the handler trait and ignore every
message. Instead, we can just do that ourselves to simplify the API.

Author: TheBlueMatt

lightning-net-tokio/src/lib.rs

@@ -600,8 +600,8 @@ mod tests {
 			msg_events: Mutex::new(Vec::new()),
 		});
 		let a_manager = Arc::new(PeerManager::new(MessageHandler {
-			chan_handler: Arc::clone(&a_handler),
-			route_handler: Arc::clone(&a_handler),
+			chan_handler: Some(Arc::clone(&a_handler)),
+			route_handler: Some(Arc::clone(&a_handler)),
 		}, a_key.clone(), &[1; 32], Arc::new(TestLogger())));
 
 		let (b_connected_sender, mut b_connected) = mpsc::channel(1);
@@ -614,8 +614,8 @@ mod tests {
 			msg_events: Mutex::new(Vec::new()),
 		});
 		let b_manager = Arc::new(PeerManager::new(MessageHandler {
-			chan_handler: Arc::clone(&b_handler),
-			route_handler: Arc::clone(&b_handler),
+			chan_handler: Some(Arc::clone(&b_handler)),
+			route_handler: Some(Arc::clone(&b_handler)),
 		}, b_key.clone(), &[2; 32], Arc::new(TestLogger())));
 
 		// We bind on localhost, hoping the environment is properly configured with a local