Do not render DevTools during SSR

[verekia]

This PR makes the DevTools client-side-only to avoid hydration issues (see #1774).

It renders ReactQueryDevtools as null during SSR, and then renders normally after mount.

I'm experiencing a failed test on my machine, even on the master branch without any change of mine:

Expected: "[\"query-2\"]"
    Received: "[\"query-1\"]"

      324 |     fireEvent.change(sortSelect, { target: { value: 'Last Updated' } })
      325 |     queries = await screen.findAllByText(/\["query-[1-3]"\]/)
    > 326 |     expect(queries[0]?.textContent).toEqual(query2Hash)
          |                                     ^
      327 |     expect(queries[1]?.textContent).toEqual(query3Hash)
      328 |     expect(queries[2]?.textContent).toEqual(query1Hash)
      329 | 

      at src/devtools/tests/devtools.test.tsx:326:37

With my changes, the failed test is different:

Expected: "[\"query-2\"]"
    Received: "[\"query-3\"]"

      324 |     fireEvent.change(sortSelect, { target: { value: 'Last Updated' } })
      325 |     queries = await screen.findAllByText(/\["query-[1-3]"\]/)
    > 326 |     expect(queries[0]?.textContent).toEqual(query2Hash)
          |                                     ^
      327 |     expect(queries[1]?.textContent).toEqual(query3Hash)
      328 |     expect(queries[2]?.textContent).toEqual(query1Hash)
      329 | 

      at src/devtools/tests/devtools.test.tsx:326:37

Maybe @prateek3255 would know what's going on?

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[TkDodo]

I'm experiencing a failed test on my machine, even on the master branch without any change of mine:

hmm, it works fine on CI 🤷

[tannerlinsley]

🎉 This PR is included in version 3.21.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀