Related to #19424
This uses the new text object support, so will only work for languages
that have `textobjects.scm`. It does not integrate with
indentation-based folding for now, and the syntax-based folds don't have
matching fold markers in the gutter (unless they are folded).
Release Notes:
- Add an editor action to fold all function bodies
Co-authored-by: Conrad <conrad@zed.dev>