Return custom scalar for StructuredText Fields

Hi,

Instead of return the scalar JsonField in the GraphQL introspection

type NewsletterBlockModelDescriptionField {
  blocks: [String!]!
  links: [String!]!
  value: JsonField!
}

Rather return a custom scalar so we can easily map it to the correct type when using graphql codegen.

scalar StructuredTextDocument
type NewsletterBlockModelDescriptionField {
  blocks: [String!]!
  links: [String!]!
  value: StructuredTextDocument!
}

In codegen we can then map the scalar explicitly to the type StructuredTextDocument from react-datocms for example.

We now have a work around involving patching the returned introspection query, but this is a bit annoying to maintain

Regards