Concurrency issue with useFind

I have found a problem with the current implementation of useFindClient.

A `fetchData` is run synchronously at first render, then useEffect run `cursor.observe({` which watch for changes on cursor.

On my component there is a concurrency issue with changes happening between the first render and the useEffect (so between the first fetchData and the observer creation)

The issue identifies useFindClient, fetchData, and cursor.observe as the relevant entry points; start by tracing the first render and the useEffect observer setup. Done means changes occurring between those steps are not missed, with the timing window covered by a regression test.

Written by the indexing model from the issue text.