[IMP] website, *: remove unused assets

*: website_blog, website_event, website_forum, website_links,
   website_livechat, website_slides, survey, web_editor

This commit removes the website navbar root widget, as the edition is
now handled in the backend through the client action and custom menus.

It removes associated widgets and their css.

See merge commit for more information.

task-2687506

addons/website/static/src/xml/website.editor.xml

@@ -1,13 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <templates id="template" xml:space="preserve">
-    <!-- Custom checkbox (material-design-like toggle) -->
-    <t t-name="website.components.switch">
-        <label class="o_switch dropdown-item m-0" t-att-for="id">
-            <input type="checkbox" t-att-id="id" t-att-checked="checked ? 'checked' : undefined"/>
-            <span/>
-            <div t-if="label"><t t-esc="label"/></div>
-        </label>
-    </t>
 
     <t t-extend="wysiwyg.widgets.link">
         <t t-jquery="#o_link_dialog_url_input" t-operation="after">