Consider using `moveBefore` (with a polyfill) for toast notifications

[mkrause]

See thread here: fkhadra/react-toastify#1200 (comment)

Currently in our ToastProvider, we use a crude workaround to prevent animations from re-running upon remount of the toast provider.

Once moveBefore is supported in browsers, we can solve this problem by just moving the elements to the <dialog> while keeping the animation state. It will take a long time before this is well-supported in all browsers, but in the meantime we could consider using the polyfill here.

[mkrause]

Also here: whatwg/html#9936 (comment)