Set functions-types-exp package to private (firebase#3262)

Author: hsubox76

packages-exp/functions-types-exp/package.json

@@ -2,6 +2,7 @@
   "name": "@firebase/functions-types-exp",
   "version": "0.0.800",
   "description": "@firebase/functions Types",
+  "private": true,
   "author": "Firebase <[email protected]> (https://firebase.google.com/)",
   "license": "Apache-2.0",
   "scripts": {