Support startTransition with refetch and fetchMore + deprecate suspensePolicy

[jerelmiller]

Fixes #10676

When using refetch or fetchMore with startTransition, the hook now behaves correctly. Because of this, suspensePolicy has been deprecated in favor of startTransition. You can now prevent the suspense boundary from being shown by wrapping the call to refetch/fetchMore in startTransition

function MyComponent() {
  const { data, refetch } = useSuspenseQuery(QUERY);
  const [isPending, startTransition] = React.useTransition();

  function handleClick() {
    startTransition(() => {
      refetch();
    });
  };

  // ...
}

Checklist:

• If this PR contains changes to the library itself (not necessary for e.g. docs updates), please include a changeset (see CONTRIBUTING.md)
• If this PR is a new feature, please reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests

[changeset-bot]

🦋 Changeset detected

Latest commit: 9884348

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

This PR includes changesets to release 1 package

Name	Type
@apollo/client	Patch

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[jerelmiller]

We no longer need access to the concast because we now resolve a custom promise on the first emit of data from the observer. This has the same previously where we'd resolve the promise on the first chunk of data for deferred queries.

[jerelmiller]

In a followup PR, I'd like to update the functionality of refetch a bit to allow for deferred queries to be incrementally rendered, as if it was kicked off the first time. The promise returned from this function should remain the same and only resolve when all data has been sent by the server, by the component should re-render with incremental data. For now, this case is not something considered in this PR.

[jerelmiller]

With suspensePolicy now gone, we can remove all of the tests that tested against it 🎉 . I've added additional tests for startTransition that mimics this behavior.

[jerelmiller]

There are still a few refactors I'd like to do at some point, but this PR is holding up enough work that I think this can be done in a follow-up PR.

[alessbell]

Being able to use startTransition instead of SuspensePolicy 🎉🎉🎉

Excited to integrate these changes with useBackgroundQuery too!