Added a copybara script to export changes to the Firebase Cocos samples from piper to git.
Added a copybara script to export changes to the Firebase Cocos samples from
piper to git.

PiperOrigin-RevId: 147895997

FirebaseExtended/cocos2dx-cpp-sample,FirebaseExtended/cocos2dx-cpp-sample,FirebaseExtended/cocos2dx-cpp-sample,FirebaseExtended/cocos2dx-cpp-sample