Implement receiving messages from add-on on the client

Reviewed By: mweststrate

Differential Revision: D34249101

fbshipit-source-id: 07297b84ed8640e3b41599726ba613b6b4e2b62e

desktop/flipper-plugin/src/test-utils/test-utils.tsx

@@ -648,5 +648,9 @@ function createServerAddOnControlsMock(): ServerAddOnControls {
     start: createStubFunction(),
     stop: createStubFunction(),
     sendMessage: createStubFunction(),
+    receiveMessage: createStubFunction(),
+    receiveAnyMessage: createStubFunction(),
+    unsubscribePlugin: createStubFunction(),
+    unsubscribe: createStubFunction(),
   };
 }