Missing css classes to menu items

Problem/Motivation

The problem that I faced was that after migrating from version 1.x to 2.x there were some missing css classes on which my theme was relying for styling the menu items.

In version 1.x inside the buildForSitemap function (https://git.drupalcode.org/project/sitemap/-/blob/8.x-1.5/src/Menu/MenuL...) there was a $class variable which sets several classes, which are not present in the 2.x version.

Proposed resolution

I have created a patch, which adds the missing classes, but without the "first" and "last" classes, which are not needed for me.