fix: meta_return on a link item

[thuyen]

Summary

Meta return doesn't work when the cursor is on a link because currently we don't handle link in the logic to find a headline or listitem node (the added test would be failing on master).

This PR factor out that logic into a reusable find_item_or_headline function and make it a bit more general.

Checklist

I confirm that I have:

• Followed the
  Conventional Commits
  specification (e.g., feat: add new feature, fix: correct bug,
  docs: update documentation).
• My PR title also follows the conventional commits specification.
• Updated relevant documentation, if necessary.
• Thoroughly tested my changes.
• Added tests (if applicable) and verified existing tests pass with
  make test.
• Checked for breaking changes and documented them, if any.

[kristijanhusak]

Thanks!