Upgrade to React 18

[KindaOK]

It's still in the RC stage, but it seems like we won't have any breaking changes. The one thing is that we will lose IE support. Not sure about the metrics and who uses IE on our site, but it might be nice to keep. The alternative is we add something so we can prerender the site server-side (in our case in the file server) and serve the page without interactivity so it works with NoScript and legacy browsers.

https://reactjs.org/blog/2022/03/08/react-18-upgrade-guide.html

[KindaOK]

Update calendar

 Warning: componentWillReceiveProps has been renamed, and is not recommended for use. See https://reactjs.org/link/unsafe-component-lifecycles for details.

      * Move data fetching code or side effects to componentDidUpdate.
      * If you're updating state whenever props change, refactor your code to use memoization techniques or move it to static getDerivedStateFromProps. Learn more at: https://reactjs.org/link/derived-state
      * Rename componentWillReceiveProps to UNSAFE_componentWillReceiveProps to suppress this warning in non-strict mode. In React 18.x, only the UNSAFE_ name will work. To rename all deprecated lifecycles to their new names, you can run `npx react-codemod rename-unsafe-lifecycles` in your project source folder.

      Please update the following components: FullCalendar