Switch to React 18 API

[nop33]

react-scrollbars-custom is not compatible with React 18. We heavily depend on this library. Thus, even though we have upgraded React to v18, we are still using the React v17 API. Once this lib becomes compatible, we can switch to the React 18 API by simply using the render method of createRoot instead of ReactDom: https://reactjs.org/blog/2022/03/08/react-18-upgrade-guide.html

I've opened an issue on the library (even though a similar one existed already:

• Incompatible with React 18 in strict mode xobotyi/react-scrollbars-custom#343
• Not working with react 18 and next js 12 getting element ref error xobotyi/react-scrollbars-custom#234

I thought of using react-custom-scrollbars-2 but it's written in JS (no types available).

[nop33]

To be completed when #72 is done.