feat: support discriminating null and undefined within useFragment

[n1ru4l]

Closes #9038

Support discriminating null and undefined within the useFragment function.

function MyComponent(props: FragmentType<typeof MyFragment> | null) {
  const data = useFragment(MyFragment, props)
  // data is `MyFragment | null`
}

function MyComponent(props: FragmentType<typeof MyFragment> | undefined) {
  const data = useFragment(MyFragment, props)
  // data is `MyFragment | undefined`
}

Before, the returned type from useFragment was always TType | null | undefined.

[changeset-bot]

🦋 Changeset detected

Latest commit: d6aed3b

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

This PR includes changesets to release 1 package

Name	Type
@graphql-codegen/client-preset	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

💻 Website Preview

The latest changes are available as preview in: https://66f31c79.graphql-code-generator.pages.dev

[github-actions]

🚀 Snapshot Release (alpha)

The latest changes of this PR are available as alpha on npm (based on the declared changesets):

Package	Version	Info
@graphql-codegen/client-preset	4.3.0-alpha-20240613090024-d6aed3bdf27fcee9415cade51ba666bc4827e049	npm ↗︎ unpkg ↗︎