Add renumber lectures button

app/views/admin/application/show.html.erb

@@ -67,6 +67,6 @@ as well as a link to its edit page.
   <% actions_template = "admin/#{page.resource.class.name.downcase}/actions" %>
 
   <% if lookup_context.template_exists?(actions_template, [], true) %>
-    <%= render actions_template %>
+    <%= render actions_template, { page: } %>
   <% end %>
 </section>

app/views/admin/course/_actions.html.erb

@@ -0,0 +1,5 @@
+<%= link_to(
+      "Renumber lectures",
+      [namespace, page.resource, :renumber_lectures],
+      class: "button",
+    ) if accessible_action?(page.resource, :renumber_lectures) %>