Bug: React 18 Strict mode does not simulate unsetting and re-setting DOM refs

<!-- Please provide a clear and concise description of what the bug is. Include screenshots if needed. Please test using the latest version of the relevant React packages to make sure your issue has not already been fixed. --> React version: 18.1.0 ## Steps To Reproduce 1. Use `<React.StrictMode>` 2. Set a ref to a JSX element in a component 3. Create a `useLayoutEffect`/`useEffect `in the component where the returned cleanup function console logs the ref 4. Save and refresh the app 5. You should have access to the ref element in the the `useLayoutEffect`/`useEffect `cleanup function during the _simulated_ unmount. <!-- Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than React. Issues without reproduction steps or code examples may be immediately closed as not actionable. --> Link to code example: https://codesandbox.io/s/proud-snow-ox4ngx?file=/src/App.js <!-- Please provide a CodeSandbox (https://codesandbox.io/s/new), a link to a repository on GitHub, or provide a minimal code example that reproduces the problem. You may provide a screenshot of the application if you think it is relevant to your bug report. Here are some tips for providing a minimal example: https://stackoverflow.com/help/mcve. --> ## The current behavior Does not unset/re-set refs in simulated unmount. This could lead to unexpected bugs in development like having double-set event listeners, i.e.` if( ref.current ){ //add eventlistener to it } `and might not match the behavior of _actually_ unmounting the DOM node as described in the docs: https://reactjs.org/docs/strict-mode.html > On the second mount, React will restore the state from the first mount. This feature simulates user behavior such as a user tabbing away from a screen and back, ensuring that code will properly handle state restoration. ## The expected behavior In normal unmounts and mounts refs are unset(before layout effects are cleaned up) and set(before layo…