.mr-auto and similar classes should use "end" and "start" instead

Problem/Motivation

Bootstrap 5 favors the use of "end" and "start" instead of "right" and "left on utility classes. This is generally intented to avoid using concepts tied to RTL languages, and replicates the semantics of Flexbox, amongst others, where "end" and "start" are not absolute but relative to the direction of the flow.

There are some instances of .mr-auto still on Radix 5.x-dev, most notably the class that separates the navbar-left and navbar-right regions on the navigation area on page.twig:

    {% block left %}
      {% if page.navbar_left %}
        <div class="mr-auto">
          {{ page.navbar_left }}
        </div>
      {% endif %}
    {% endblock %}

This issue could also check for other missing utility classes (padding-left, etc)