FEATURE: show user status on group pages (#19323)

This adds live user status to /g/{group-name} routes.

app/serializers/group_user_serializer.rb

@@ -8,10 +8,22 @@ class GroupUserSerializer < BasicUserSerializer
              :last_posted_at,
              :last_seen_at,
              :added_at,
-             :timezone
+             :timezone,
+             :status
+
+  def timezone
+    user.user_option.timezone
+  end
 
   def include_added_at?
     object.respond_to? :added_at
   end
 
+  def include_status?
+    SiteSetting.enable_user_status && user.has_status?
+  end
+
+  def status
+    UserStatusSerializer.new(user.user_status, root: false)
+  end
 end