Decrease bundle sizes

[nwalters512]

This PR makes two changes to improve the size of the bundles we ship to clients:

• Switch from moment/react-moment to date-fns and a custom component to render auto-updating relative dates.
• Individually import Font Awesome icons to avoid including every icon, as tree-shaking appears to not be working properly with the version of Next.js that we're on.

I also ripped out some old code for April Fools and workshop announcements.

Together, this more than halves the amount of parsed code in many of our page's bundles. For instance, the Queue page went from 570KB of JS to 319KB. Other pages, like the User Settings page, saw even greater improvements.

[vercel[bot]]

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