buildClientSchema implementation

[SafeEval]

The reference implementation of GraphQL has a utility function, buildClientSchema, that is missing from this implementation.

The function converts the results of an introspection query to a GraphQLSchema instance.

buildClientSchema is key for schema federation (#492) and stitching (#329, #435), demonstrated by the gatsby-source-graphql package.

Including this function would allow downstream packages to add federation and stitching features, and the creation of GraphQL analysis tools written in Go.

While federation and stitching might be out of scope for this project, the buildClientSchema building block seems within scope, being part of the reference implementation.

Thanks for the great work on this package!

[MoritzGruber]

If someone es is looking for this, there is a external package that does this: https://github.com/jensneuse/graphql-go-tools

[jufemaiz]

If someone es is looking for this, there is a external package that does this: https://github.com/jensneuse/graphql-go-tools

@MoritzGruber any tips there?