Read GraphQL schema from `graphql-config` file

[Jovi De Croock]

Summary

A lot of people in the ecosystem are opted into the graphql-config way of things, rather than always relying on folks passing fuse dev --client --schema x we should attempt to read the graphql-config if there is one present and use the schema/url/... we derive from there.

This is all neatly packaged into their library authors guide so we can start using it immediately 🙌