Upgrade to React v18

[kgryte]

Upgrade to React v18.

Currently, this is blocked by

• @mui/styles: we use this exclusively for SSR. We should investigate whether we can avoid using this and perform SSR using an alternative means.
• @mui/material: still has a peer dep on React v17.0.0. See tracking issue: [internal] Checklist of new opportunities with React 18 release mui/material-ui#29844.

[kgryte]

Re: SSR. This guide may be useful: https://mui.com/material-ui/guides/server-rendering/.