Add threads icon and update Font Awesome

[derme302]

• Font Awesome no longer offer free CDN support for newer versions, so this moves the files into the font
  • Thought about adding support for Font Awesome Kits, but they aren't able to be cached by clients. No performance improvement compared to serving the font with the website
• Updates all icons to use the newer Font Awesome fa-brands fa-solid tags
• Adds the threads icon to the social media sidebar
• Adds threads to the example site