feat: Implement @_unmask directives to unmask fragment types

[kitten]

Supersedes #28
Resolves #23

Summary

Fragments will now not be masked when they’re annotated with @_unmask. This will cause all their types derived by FragmentOf<> and in parent documents to be fully unwrapped and unmasked.

const fragment = graphql(`
  fragment TodoFields on Todo @_unmask {
    id
    text
  }
`);

//: { id: string | number, text: string }
type fragmentType = FragmentOf<typeof fragment>;

const query = graphql(`
  query {
    todo {
      ...TodoFields
    }
  }
`, [fragment]);

//: { todo: { id: string | number, text: string } }
type resultType = ResultOf<typeof fragment>;

This PR also improves the readability of the TodoDocumentNode generics. Instead of the third generic being a full fragment definition, it'll now be displayed with a different syntax, i.e.

{
  fragment: 'FragmentName',
  on: 'Type',
  masked: true
}

Set of changes

• Refactor how reference types for definitions are used in selection types
• Update type of fragment definition (i.e. $tada.definition)
• Add support for @_unmask directive
• Filter @_unmask directives from fragment definitions

[changeset-bot]

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Latest commit: 008c137

The changes in this PR will be included in the next version bump.

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