Upgraded to React 18; first upgraded to MUI 5

I upgraded to React 18, but to do it I needed to migrate from material-ui-4 to mui-5. This was a little more involved than I had hoped, so I had to take it slow. The migration documentation for mui-5 described everything that needed to be done, I just needed to work my way through it.

The difficult piece was handling the styles. The new approach for styling in mui5 is slick, but it's not an easy migration. I've decided to just get through with the process and then use the new approach a bit later. If this was a high volume site I'd handle it a bit differently ;)

To cross the finish line I had to start using Emotion. I followed the advice in this blog entry: Next.Js + MUI v5 tutorial .