Refactor admin settings, add all service settings

app/views/admin/settings/services/_discourse.html.erb

@@ -0,0 +1,17 @@
+<h3>Discourse</h3>
+<ul role="list">
+  <%= render FormElements::FieldsetToggleComponent.new(
+    form: f,
+    attribute: :discourse_enabled,
+    enabled: Setting.discourse_enabled?,
+    title: "Enable Discourse integration",
+    description: "Discourse configuration present and features enabled"
+  ) %>
+</ul>
+<% if Setting.discourse_enabled? %>
+  <%= render FormElements::FieldsetComponent.new(title: "Public URL") do %>
+    <%= f.text_field :discourse_public_url,
+      value: Setting.discourse_public_url,
+      class: "w-full", disabled: true %>
+  <% end %>
+<% end %>