Function connect_submodule_work_tree_and_git_dir 

pub fn connect_submodule_work_tree_and_git_dir(
    grit_bin: &Path,
    work_tree: &Path,
    super_git_dir: &Path,
    cfg: &ConfigFile,
    submodule_name: &str,
    sub_worktree: &Path,
) -> Result<()>

Writes the gitfile and core.worktree for a submodule using configured submodule.<name>.gitdir.