Add backoffice-no-script.css

This makes certain elements visible when JavaScript is disabled.

src/backoffice/static/backoffice-no-script.css

+div.collapse:not(.show) {
+  display: block !important;
+}

src/backoffice/templates/backoffice/base.html

@@ -17,6 +17,11 @@
           type="text/css"
           href="{% static 'vendor/bootstrap-icons/bootstrap-icons.min.css' %}">
     <link rel="stylesheet" type="text/css" href="{% static 'backoffice.css' %}">
+    <noscript>
+      <link rel="stylesheet"
+            type="text/css"
+            href="{% static 'backoffice-no-script.css' %}">
+    </noscript>
     {% if uses_map %}
       {% include "core/map_header.html" %}
     {% endif %}