Remove dependency on react-redux-form

This completes the port to Formik (🤞). I'm really sorry to see RRF go, and had a couple of nostalgic moments refactoring the code over the past weeks, thinking back to the memorable Christmas break when I wrote the first cut of our app -- I'm amazed at what the library let a clueless novice like me do, and sincerely thankful for the work @davidkpiano and team put into it. I'm grateful, too, for their patient help and generous support over the years; this humble application just wouldn't exist without them, and I wouldn't know close to what little I do. Many, many heartfelt thanks! ❤️

packages/builder/package.json

@@ -42,7 +42,6 @@
     "react-modal": "^3.11.1",
     "react-monaco-editor": "^0.35.0",
     "react-redux": "^7.1.3",
-    "react-redux-form": "^1.16.14",
     "react-scripts": "3.4.1",
     "react-transition-group": "^4.3.0",
     "reactstrap": "^8.4.1",