Process and render messages when a plugin is opened

Summary: This introduces the necessary UI changes, to kick off and render event progressing process where needed

Reviewed By: jknoxville

Differential Revision: D19175450

fbshipit-source-id: 61e3e8f59eeebf97eedbe715fa7db320286543e2

src/test-utils/createMockFlipperWithPlugin.tsx

@@ -72,8 +72,7 @@ export async function createMockFlipperWithPlugin(
   );
 
   // yikes
-  client._deviceSet = true;
-  client.getDeviceSync = () => device;
+  client._deviceSet = device;
   client.device = {
     then() {
       return device;