Function build_menu_items

pub fn build_menu_items(
    name: &str,
    target: &Option<String>,
    n_panes: usize,
    n_windows: usize,
) -> (String, Vec<(String, Action)>)

Build (title, items) for a menu screen by name. n_panes / n_windows gate destructive entries so we never offer to kill the last one.