feat: add MessageCenterHandler (#770)

Co-authored-by: Peng Xiao <pengxiao@freewheel.tv>

packages/data-center/src/message/message.ts

@@ -32,5 +32,8 @@ export class MessageCenter extends Observable<string> {
 
   public onMessage(callback: (message: Message) => void) {
     this.on('message', callback);
+    return () => {
+      this.off('message', callback);
+    };
   }
 }