React 18 (#863)

* gymnastics to make theme script work with react 18 hydration

* try next 12.1.3 canary to fix SSG head tags?

* revert theme script changes

* next 12.1.3-canary.3

* double-revert some of the use-theme.tsx changes

* separate theme restoration script & move to _document

* bump next

* bump next (again)

* clean up some theme stuff

* use hashed image URLs in webmanifest and feeds

* text experimental react config

* Update ThemeScript.tsx

* switch selfie image to `layout="raw"`

* use `layout="raw"` for all non-imported images

* revert raw images in some places, messes up responsiveness

* fix nitpicky "no divs inside buttons" html validation error

* fix react-player hydration errors

* fix hydration errors from server/client time zone differences

* clean up hydration fixes

* Update format-date.ts

* last-minute cleanup

components/ThemeToggle/ThemeToggle.tsx

@@ -92,10 +92,10 @@ const ThemeToggle = ({ id = "nav", className }: ThemeToggleProps) => {
     config: springProperties.springConfig,
   });
 
-  // render a dummy button until we're fully mounted and self-aware
+  // render a blank div of the same size to avoid layout shifting until we're fully mounted and self-aware
   if (!hasMounted) {
     return (
-      <Button aria-hidden={true} disabled={true}>
+      <Button as="div" aria-hidden={true}>
         <div className={className} />
       </Button>
     );