portal: display additional links configured in yaml

app/portal/templates/base.html.j2

@@ -168,6 +168,20 @@
                     </li>
                 </ul>
             </div>
+            {% if config['ADDITIONAL_SIDEBAR_LINKS'] %}
+            <h6 class="sidebar-heading d-flex justify-content-between align-items-center px-3 mt-4 mb-1 text-muted">
+                <span>Extras</span>
+            </h6>
+            <ul class="nav flex-column">
+              {% for link in config['ADDITIONAL_SIDEBAR_LINKS'] %}
+                  <li class="nav-item">
+                    <a class="nav-link" href="{{ link['url'] }}">
+                        {{ icon(link['icon']) }} {{ link['label'] }}
+                    </a>
+                  </li>
+              {% endfor %}
+            </ul>
+            {% endif %}
         </nav>
 
         <main class="col-md-9 ms-sm-auto col-lg-10 px-md-4">