portal: additional buttons on list pages

link to onion services page from origin page
link to previews of distribution lists from lists

app/portal/origin.py

@@ -89,10 +89,15 @@ def origin_list():
     origins = Origin.query.order_by(Origin.domain_name).all()
     return render_template("list.html.j2",
                            section="origin",
-                           title="Origins",
+                           title="Web Origins",
                            item="origin",
                            new_link=url_for("portal.origin.origin_new"),
-                           items=origins)
+                           items=origins,
+                           extra_buttons=[{
+                               "link": url_for("portal.origin.origin_onion"),
+                               "text": "Onion services",
+                               "style": "onion"
+                           }])
 
 
 @bp.route("/onion")