Function validate_encoded_submodule_git_dir 

pub fn validate_encoded_submodule_git_dir(
    work_tree: &Path,
    cfg: &ConfigFile,
    git_dir: &Path,
    submodule_name: &str,
    super_git_dir: &Path,
) -> Result<()>

Validates an encoded submodule gitdir path when submodulePathConfig is enabled.