Docs landing page redesign (#2847)

* Import PR #2805 changes

* Update Docs landing page design

* Minor style fixes

* Fix tests

* Add links to other cards, fix icons, and tighten up mobile styles

* Add fonts and clean up a few styles to better match marketing site

* Fix test

* Remove marketing fonts

This was an attempt to get the fonts used in the landing page that are added by the injected marketing header to work on the PR previews. The font are restricted by CORS and my attempt at adding them here didn’t work either, so reverting those changes.

* Move elements per feedback

The “Browse all docs” section was moved above the marketing callout and need help section

* Add feedback widget

* Fix fonts