Restore the editor on the website

[tamasfe]

With the switch to vitepress, the web editor has been removed.

I intend to put it back, but at least with some kind of LSP integration for the feature showcase.

The progress so far:

• [x] A page with CodeMirror.
• [x] Taplo library for formatting.
• [x] Taplo LSP working in a web worker.
• [ ] An actually working LSP bridge that works with CodeMirror 6 and web workers and is not tied to websockets.