feat: create funnel-builder extension

Author: adrians5j

extensions/funnel-builder/extension.json

@@ -14,6 +14,10 @@
   },
   "additionalNotes": {
     "messages": [
+      {
+        "text": "This extension requires additional dependencies. Run %s in your project root to install them.",
+        "variables": ["yarn"]
+      },
       {
         "text": "Learn more about the extension in %s.",
         "variables": ["extensions/funnelBuilder/README.md"]