chore(datafile manager): Remove react native datafile manager entry from package.json (#459)

Summary:

Remove package.json entry point for RN datafile manager.

Test plan:

Existing tests

Author: mjc1283

packages/datafile-manager/package.json

@@ -8,7 +8,6 @@
   },
   "main": "lib/index.node.js",
   "browser": "lib/index.browser.js",
-  "react-native": "lib/index.react_native.js",
   "types": "lib/index.d.ts",
   "directories": {
     "lib": "lib",