Closes
https://linear.app/zed-industries/issue/Z-2513/panic-in-refresh-inlay-hints

* Filter out queries for outdated buffers just before hint tasks spawn:
  multicaret edits might emit standalone events simultaneously
* Only spawn inlay update tasks for visible buffers with corresponding
  language
* Do not spawn tasks for local projects' buffers without LSP servers

Release Notes:

- N/A