Feature: [lexical-website] Upgrade docusaurus-plugin-typedoc and typedoc-plugin-markdown

[etrepum]

It seems that a lot of improvements have happened to docusaurus-plugin-typedoc, seems to fix some issues that I've noticed with how the docs are generated and organized, but it's a backwards incompatible change.

We should:

• Upgrade these packages
• Update the configuration accordingly (sidebars in particular, but we may also be able to get rid of some of our other plugins that exist just to work around previous bugs)
• Update all of the static links to the documentation in the monorepo (the URL structure changes, but we also only have these references in the README files so it's not a big task)
• Consider adding redirect routes in lexical-website so that old links redirect to their new location rather than 404

[TropicolX]

Hi @etrepum! Can I be assigned to work on this problem?