🔨(project) add json, cjs and js extensions to prettier config

Prettier had some missing extensions in the config, this commit
added them, we then prettified the whole project. We
ignore the `cunningham-tokens` files.

apps/demo/tsconfig.json

@@ -1,9 +1,9 @@
 {
   "extends": "@openfun/typescript-configs/react.json",
   "compilerOptions": {
-    "noEmit": true,
+    "noEmit": true
   },
   "include": ["src"],
-  "exclude": ["node_modules","dist"],
+  "exclude": ["node_modules", "dist"],
   "references": [{ "path": "./tsconfig.node.json" }]
 }