React 18 Suspense unable to track when a promise completes causing SWR failure

When working with [SWR](https://swr.vercel.app/) with `React 17`, you could pass to `useSwr` on `onSuccess` parameter which would assign a completion function so that when an async call finished, you could take some action (for example, when not using Relay, you can trigger another component to begin loading data based on the returned data from `useSwr`. After [this lengthy issue](https://github.com/vercel/swr/issues/1733) with @promer94, one of the devs on SWR, we found an ugly workaround with `useEffect` and some negative logic, but it is not satisfactory and will always be hard to reason about as well as do so similar things without introducing bugs. To quote @promer94, `i think we need more time to understand concurrent mode before we change current api design`. This feels to me like either we don't understand how Suspense works, or there is a serious usability issue if not using Relay. It's summarized best here: https://github.com/vercel/swr/issues/1733#issuecomment-1001391484 . Assuming this is correct, there is no determinant way to know when components suspense promise completes, and no way to act on that which would be required in multi-component scenarios. The issue mentioned above https://github.com/vercel/swr/issues/1733 explains in more detail the problem, and the example code that demonstrates it by having to do the ugly workaround for not having `onSuccess` is in this repo: https://github.com/pkellner/pluralsight-react-18-suspense-swr-problem/blob/master/src/components/CityListItems.js If you want to see the program working you can view it on this link. Notice that after the city list loads, the first city becomes selected. That was trivial using React 17 with SWR and really hard with React 18 and Suspense enabled. https://pluralsight-react-18-first-look.peterkellner.net/# The source for the app with Suspense is here: https://github.com/pkellner/airquality