Basic skeleton for no diff found

Summary:
- populate the state
- will render some UI that you can reload
- next up showing the diff number and title

Differential Revision: D26477472

fbshipit-source-id: d5c5175771c324c9f893a6b6c6a14a40a2f0f0fe

desktop/static/icons.json

@@ -529,6 +529,7 @@
     16
   ],
   "refresh-right": [
+    12,
     16
   ],
   "hourglass": [