templates: add progressbar role to form steps (#40921)

templates/wcs/front/formdata_steps.html

@@ -1,6 +1,12 @@
 {% load i18n %}
 <header id="steps" class="wcs-steps steps-{{page_labels|length}}">
-  <h2>{% trans "Steps" %}</h2>
+  <h2 id="steps--title">{% trans "Steps" %}</h2>
+  <div role="progressbar"
+    aria-labelledby="steps--title"
+    aria-valuemin="1"
+    aria-valuenow="{{ current_page_no }}"
+    aria-valuemax="{{ page_labels|length }}"
+    aria-valuetext="Étape {{ current_page_no }} : {{ page_labels|get:current_page_index }}">
     {% block steps-list %}
       <ol class="wcs-steps--list">
         {% for page_label in page_labels %}
@@ -31,4 +37,5 @@
         {% endfor %}
       </ol>
     {% endblock %}
+  </div>
 </header>