Fully implement flow static analysis for react native

Now that flow has better support for Typescript, we need to update our mobile-native configuration to do static analysis at the CI level and catch any type errors / null

• Upgrade our type script typing and make sure we've got our stack up to date.
• Make the app compile with type script
• Add static analysis checking to the CI flow
• Make sure the app builds and deploys
• Roll out complete type checking so we can catch all the errors
• Enable Prettier at the CI level