feat: new background work process

This removes all previous dependencies on RabbitMQ and the need to run separate cron and requeueing processes.

app/scheduled_tasks/check_all_dns_scheduled_task.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class CheckAllDNSScheduledTask < ApplicationScheduledTask
+
+  def call
+    Domain.where.not(dns_checked_at: nil).where("dns_checked_at <= ?", 1.hour.ago).each do |domain|
+      logger.info "checking DNS for domain: #{domain.name}"
+      domain.check_dns(:auto)
+    end
+
+    TrackDomain.where("dns_checked_at IS NULL OR dns_checked_at <= ?", 1.hour.ago).includes(:domain).each do |domain|
+      logger.info "checking DNS for track domain: #{domain.full_name}"
+      domain.check_dns
+    end
+  end
+
+end