Add first_reply_created event in conversation (#4576)

db/migrate/20220513145010_add_first_reply_activity_at_to_conversation.rb

@@ -0,0 +1,23 @@
+class AddFirstReplyActivityAtToConversation < ActiveRecord::Migration[6.1]
+  def change
+    add_column :conversations, :first_reply_created_at, :datetime
+    add_index :conversations, :first_reply_created_at
+
+    # rubocop:disable Rails/SkipsModelValidations
+    ::Conversation.update_all(first_reply_created_at: Time.now.utc)
+    # rubocop:enable Rails/SkipsModelValidations
+
+    backfill_first_reply_activity_at_to_conversations
+  end
+
+  private
+
+  def backfill_first_reply_activity_at_to_conversations
+    ::Account.find_in_batches do |account_batch|
+      Rails.logger.info "Migrated till #{account_batch.first.id}\n"
+      account_batch.each do |account|
+        Migration::ConversationsFirstReplySchedulerJob.perform_later(account)
+      end
+    end
+  end
+end