WD-1299 use new vanilla layout on design ubuntu com site

[pedoch]

Done

• Use the new layout on the following pages:
  • Home
  • Accessibility
  • Contribute
  • Font
  • Resources
  • 404
• Minor fixes on the resources page
  • Remove the Illustration section
  • Make the Icon set section dark mode switch hide on medium and small screens

QA

• Open the site and inspect the pages for the new layout
• Navigate to /resources
• Check if the icon set switch hides on medium and small screens
• Check that the illustration section has been removed

Issue / Card

• WD-1299
• WD-1297

[webteam-app]

Demo starting at https://design-ubuntu-com-274.demos.haus