Move redirects-raw.txt file from frontpage to storybook monorepo

[kylegach]

Colocating the redirects with the docs content itself has multiple benefits:

• Most importantly, it's possible to update the redirects in the same PR that the content is affected
  • This prevents having to coordinate updates across multiple repos, which can be tricky to do without causing 404s and the like at least temporarily
• This also versions the redirects
  • Only the "latest" version of the docs site has functioning redirects
  • So if you make TOC changes in another version (e.g. 7.0, at the time of writing), you must (currently) only represent those changes in redirects after that version goes stable.
  • If redirects were versioned, they could be updated alongside TOC changes and automatically become active once the release goes stable
  • We could also (possibly) use those versioned redirects to build a final version of redirects that works for the versioned sites, not just the "latest" one