Explicitly exclude types_generated/ from "exports" (#51121)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/51121

Previously could match via the `"./*"` subpath when `"react-native-strict-api"` is not set. Only the entry point `./types_generated/index.d.ts` should be exposed.

Changelog: [Internal]

Reviewed By: cortinico

Differential Revision: D74242716

fbshipit-source-id: 232c90f34fafe8fdf1a5a7ef1fec4acc191525b4

packages/react-native/package.json

@@ -64,6 +64,7 @@
     "./src/*": null,
     "./third-party-podspecs/*": null,
     "./types/*": null,
+    "./types_generated/*": null,
     "./package.json": "./package.json"
   },
   "jest-junit": {