Make react-native-codegen work on Windows within BUCK
Make react-native-codegen work on Windows within BUCK

Summary:
Changelog
[General][Internal] - Make react-native-codegen work on Windows within BUCK

This makes react-native code-gen work on Windows - by basically filling in some necessary windows commands for the existing bash/shell ones

Reviewed By: cortinico, cipolleschi

Differential Revision: D40268750

fbshipit-source-id: 0db7597999ec8108babf56abed436f6dc7789cce

facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native