Add test to sync RN github flow configs
Add test to sync RN github flow configs

Summary:
Adds three more tests:

* compare RN github ios and android flowconfigs
* compare xplat/js ios flowconfig with RN github ios flowconfig
* compare xplat/js android flowconfig with RN github android flowconfig

Reviewed By: TheSavior

Differential Revision: D9191176

fbshipit-source-id: 34f3644ffc5a26d3bdfd94b6c05a138407aaedeb

facebook/react-native,pandiaraj44/react-native,hoangpham95/react-native,hammerandchisel/react-native,hammerandchisel/react-native,janicduplessis/react-native,janicduplessis/react-native,arthuralee/react-native,exponent/react-native,facebook/react-native,arthuralee/react-native,facebook/react-native,exponentjs/react-native,exponent/react-native,arthuralee/react-native,janicduplessis/react-native,myntra/react-native,javache/react-native,facebook/react-native,facebook/react-native,hammerandchisel/react-native,javache/react-native,arthuralee/react-native,myntra/react-native,pandiaraj44/react-native,exponent/react-native,pandiaraj44/react-native,hammerandchisel/react-native,janicduplessis/react-native,javache/react-native,exponentjs/react-native,javache/react-native,exponent/react-native,exponentjs/react-native,exponentjs/react-native,hoangpham95/react-native,hammerandchisel/react-native,arthuralee/react-native,hoangpham95/react-native,janicduplessis/react-native,myntra/react-native,javache/react-native,exponentjs/react-native,janicduplessis/react-native,pandiaraj44/react-native,exponent/react-native,janicduplessis/react-native,javache/react-native,pandiaraj44/react-native,facebook/react-native,hoangpham95/react-native,javache/react-native,hammerandchisel/react-native,javache/react-native,myntra/react-native,myntra/react-native,pandiaraj44/react-native,facebook/react-native,hoangpham95/react-native,hammerandchisel/react-native,exponent/react-native,exponentjs/react-native,hammerandchisel/react-native,exponentjs/react-native,exponent/react-native,janicduplessis/react-native,hoangpham95/react-native,pandiaraj44/react-native,myntra/react-native,exponent/react-native,exponentjs/react-native,hoangpham95/react-native,myntra/react-native,hoangpham95/react-native,facebook/react-native,myntra/react-native,facebook/react-native,pandiaraj44/react-native,myntra/react-native,javache/react-native