Create VR Call Hub Flipper plugin

Summary: As part of BE, this diff creates the initial Flipper plugin for VR Call Hub using `scarf flipper-plugin` from the tutorial https://www.internalfb.com/intern/staticdocs/flipper/docs/tutorial/intro/

Differential Revision: D42146201

fbshipit-source-id: 8bc52184b21b2e47304f694068d11fd962b07b9d

desktop/static/icons.json

@@ -658,5 +658,8 @@
   ],
   "square-ruler": [
     16
+  ],
+  "phone": [
+    16
   ]
 }