Summary:
We only need to ensure `react-native-codegen` is a direct dependency of `react-native` in open source releases. Otherwise, we can use the package from source at `packages/react-native-codegen`.
Changelog: [Internal]
Reviewed By: fkgozali
Differential Revision: D31190817
fbshipit-source-id: 527b1c370a35c3efad2448b510172a87c7345ee2