[FIX] website_forum: add summernote for non designer

In saas-6 the editor assets were always included, in 9.0 only for
designer but if website_forum is installed it should also be included.

fixes #9402
closes #9852

note: should not be forward ported after saas-8

addons/website_forum/views/website_forum.xml

@@ -42,6 +42,12 @@
 <!-- Page Index -->
 <template id="header" name="Forum Index">
     <t t-call="website.layout">
+        <t groups="base.group_website_designer" t-set="is_designer" t-value="True"/>
+        <t t-if="not is_designer">
+            <t t-set="head">
+                <t t-call-assets="web_editor.summernote"/>
+            </t>
+        </t>
         <div t-if="is_public_user and not forum_welcome_message" class="forum_intro">
             <div t-field="forum.welcome_message"/>
         </div>