Function parse_worktree_ref 

pub fn parse_worktree_ref(
    maybe: &str,
) -> (RefWorktreeType, Cow<'_, str>, Option<Cow<'_, str>>)

Parse maybe_worktree_ref like Git parse_worktree_ref.

Returns worktree kind, bare ref name for storage, and worktree id for worktrees/<id>/….