wcs: add template blocks for text parts of tracking code cell (#35623)

combo/apps/wcs/templates/combo/wcs/tracking_code_input.html

@@ -1,8 +1,11 @@
 {% load i18n %}
 {% block cell-content %}
 <div class="wcs-tracking-code-input">
+ {% block title %}
  <h2>{% trans 'Tracking Code' %}</h2>
+ {% endblock %}
  <form data-wcs-url="{{ url }}" method="post" action="{{ site_base }}{% url 'wcs-tracking-code' %}">
+  {% block intro-text %}
   <p>
     {% blocktrans %}
     A tracking code is attached to all your forms, it is there to help you in
@@ -10,6 +13,7 @@
     a tracking code, you can enter the code in the entry below:
     {% endblocktrans %}
   </p>
+  {% endblock %}
   <input id="_cell_url_{{ cell.id }}" name="url" value="" type="hidden"/>
   <input name="cell" value="{{ cell.id }}" type="hidden"/>
   <div id="_cell_error_{{ cell.id }}" class="errornotice" style="display: none">