Improve entity pager accessibility for screen readers

Attaching patches that can be used with composer against:

• Entity Pager 2.0.x — this patch mimics the current state of the MR itself
• Entity Pager 8.x-1.x — because the 2.0.x branch MR was unable to apply cleanly, and needed a manual reroll.

Should this part be in the NAV element, since it's not links?

  {% if display_count and current %}
    {% block count %}
      {% trans %}
        <p class="entity-pager-item-count">{{ current }} of {{ count }}</p>
      {% endtrans %}
    {% endblock %}
  {% endif %}

Also, our minimum core requirement is about to change to 10.1, so we should use the twig filter for the ID -- see https://www.drupal.org/node/3363551 → .