Add CI step to run future extension tests (#1214)

Signed-off-by: Sebastian Malton <sebastian@malton.name>

extensions/example-extension/package.json

@@ -10,7 +10,8 @@
   },
   "scripts": {
     "build": "webpack --config webpack.config.js",
-    "dev": "npm run build --watch"
+    "dev": "npm run build --watch",
+    "test": "echo NO TESTS"
   },
   "dependencies": {
     "react-open-doodles": "^1.0.5"