Return X/Twitter Link Previews per stevenlafl

Adds the link previews with headline and description back to X posts. All requests are done with the Fetch API (to t.co that twitter provides and follows the redirect to the final destination, scraping the opengraph data) and cached in local browser store.

Source code, including a Chrome version is here: https://github.com/stevenlafl/return-x-link-preview