(breaking) - Remove pollInterval option from urql

[kitten]

Resolves #531

Summary

This PR removes the pollInterval option from @urql/core and all bindings. Generally it isn't hard to replace pollInterval in user-land with even more correct behaviour, as it can ultimately read the results of the bindings and react to those accordingly.

React / Preact replacement

This just demonstrates that it's rather simple to replace the implementation in React-land.

const [result, executeQuery] = useQuery(...);

useEffect(() => {
  if (!result.fetching) {
    const id = setTimeout(() => executeQuery({ requestPolicy: 'network-only' }), 5000);
    return () => clearTimeout(id);
  }
}, [result.fetching, executeQuery]);

NOTE re #531: It's worth noting that this PR doesn't resolve the issue explicitly, however we see it as much easier to implement effects in user-land that call executeQuery to refresh the results on an interval.

Set of changes

• Remove pollInterval from @urql/core
• Remove pollInterval from useQuery in urql
• Remove pollInterval from useQuery in @urql/preact
• Remove pollInterval from useQuery in @urql/vue

[changeset-bot]

🦋 Changeset detected

Latest commit: d27c1a4

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

This PR includes changesets to release 6 packages

Name	Type
@urql/core	Major
@urql/vue	Minor
urql	Major
@urql/preact	Major
@urql/svelte	Patch
next-urql	Major

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[JoviDeCroock]

A few mentions of pollInterval in the vue tests but generally looks awesome! We should later amend the docs with the replacement.