Use better semantics in the HTML container, like core's menus <nav>

Problem/Motivation

A menu should be a <nav> HTML tag, like rendered by Drupal core.

From https://www.jstree.com/ it seems that the CSS id is used, "a <div> is enough" doesn't mean you should use it instead of <nav>. If a div is needed, can't we also put the nav inside?