Refactor – Replace Apollo Generator with GraphQL Code Generator

[simenandre]

To improve developer experience, I think it would be better to utilize GraphQL Code Generator instead of Apollo's Generator.

What makes GrahpQL Code Generator better?

Generally, a much better developer experience; IMHO, the best part is that GraphQL Code Generator generates hooks based on operation files (graphql files with queries).

@dotansimha has also made a nice list of features and differences for further reference. apollographql/apollo-tooling#2053