FEATURE: New way to dismiss new topics (#11927)

This is a try to simplify logic around dismiss new topics to have one solution to work in all places - dismiss all-new, dismiss new in a specific category or even in a specific tag.

spec/fabricators/dimissed_topic_user.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+Fabricator(:dismissed_topic_user) do
+  user
+  topic
+  created_at { Time.zone.now }
+end