Consume changed plugins message in the UI

Summary: Relay message to the React app via postmessage. Later, we will subscribe to these messages and update the plugins

Reviewed By: lblasa

Differential Revision: D39539590

fbshipit-source-id: c6742e45330e71b63c135c0267e6e9c5817fc9ff

desktop/static/index.dev.html

@@ -68,6 +68,13 @@
         suppressErrors = true;
       });
 
+      socket.on('plugins-source-updated', (pluginsChanged) => {
+        window.postMessage({
+          type: 'plugins-source-updated',
+          data: pluginsChanged
+        })
+      })
+
       function openError(text) {
         if (suppressErrors) {
           return;
@@ -105,4 +112,4 @@
   </script>
 </body>
 
-</html>
+</html>