Add Fastlane

[robinheinze]

Add example Fastfiles for iOS and Android, along with documentation for getting started on CI/CD.

[flexbox]

@robinheinze Maybe you can ping @eduplus on the #react-native-ci channel on Slack. There is example on this repo with fastlane integration https://github.com/solinor/react-native-ci

[robinheinze]

The Chain React Conf app is also a good example, as we had Fastlane setup, as well as Automated Testflight builds using CircleCI https://github.com/infinitered/ChainReactApp2019

[plrdev]

Thanks for the ping @flexbox - I would be more than happy to coordinate so that react-native-ci would integrate well with ignite (bowser). Up to you how you want to go about it.

[hedgerh]

Would love to contribute back to this, but I'm a newb to RN. What would out-of-the-box CI/CD look like in Bowser? Need to set it up in my own project, so happy to contribute it back.