FIX: Show Settings button if plugin has settings (#9728)

It used to check if the plugin has an enabled_setting.

app/serializers/admin_plugin_serializer.rb

@@ -8,6 +8,7 @@ class AdminPluginSerializer < ApplicationSerializer
              :admin_route,
              :enabled,
              :enabled_setting,
+             :has_settings,
              :is_official
 
   def id
@@ -38,6 +39,10 @@ class AdminPluginSerializer < ApplicationSerializer
     object.enabled_site_setting
   end
 
+  def has_settings
+    SiteSetting.plugins.values.include?(id)
+  end
+
   def include_url?
     url.present?
   end