Add Rails standard ApplicationJob for consistency

New Rails apps come with this class already, the job generator creates
it for every new job and Rubocop requires it as well. Let's make our
lives easier and use the same structure as other Rails projects. This
class may be handy one day.

.rubocop_todo.yml

@@ -684,19 +684,6 @@ Rails/ApplicationController:
   Exclude:
     - 'engines/dfc_provider/app/controllers/dfc_provider/base_controller.rb'
 
-# Offense count: 6
-# This cop supports unsafe autocorrection (--autocorrect-all).
-Rails/ApplicationJob:
-  Exclude:
-    - 'app/jobs/bulk_invoice_job.rb'
-    - 'app/jobs/heartbeat_job.rb'
-    - 'app/jobs/order_cycle_closing_job.rb'
-    - 'app/jobs/order_cycle_notification_job.rb'
-    - 'app/jobs/report_job.rb'
-    - 'app/jobs/subscription_confirm_job.rb'
-    - 'app/jobs/subscription_placement_job.rb'
-    - 'spec/services/job_processor_spec.rb'
-
 # Offense count: 1
 # This cop supports unsafe autocorrection (--autocorrect-all).
 Rails/ApplicationMailer:

app/jobs/application_job.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+# Rails standard class for common job code.
+class ApplicationJob < ActiveJob::Base
+  # Automatically retry jobs that encountered a deadlock
+  # retry_on ActiveRecord::Deadlocked
+
+  # Most jobs are safe to ignore if the underlying records are no longer available
+  # discard_on ActiveJob::DeserializationError
+end

app/jobs/bulk_invoice_job.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class BulkInvoiceJob < ActiveJob::Base
+class BulkInvoiceJob < ApplicationJob
   def perform(order_ids, filepath)
     pdf = CombinePDF.new
 

app/jobs/heartbeat_job.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class HeartbeatJob < ActiveJob::Base
+class HeartbeatJob < ApplicationJob
   def perform
     Spree::Config.last_job_queue_heartbeat_at = Time.now.in_time_zone
   end

app/jobs/order_cycle_closing_job.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-class OrderCycleClosingJob < ActiveJob::Base
+class OrderCycleClosingJob < ApplicationJob
   def perform
     return if recently_closed_order_cycles.empty?
 

app/jobs/order_cycle_notification_job.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 # Delivers an email with a report of the order cycle to each of its suppliers
-class OrderCycleNotificationJob < ActiveJob::Base
+class OrderCycleNotificationJob < ApplicationJob
   def perform(order_cycle_id)
     order_cycle = OrderCycle.find(order_cycle_id)
     order_cycle.suppliers.each do |supplier|

app/jobs/subscription_confirm_job.rb

@@ -3,7 +3,7 @@
 require 'order_management/subscriptions/summarizer'
 
 # Confirms orders of unconfirmed proxy orders in recently closed Order Cycles
-class SubscriptionConfirmJob < ActiveJob::Base
+class SubscriptionConfirmJob < ApplicationJob
   def perform
     confirm_proxy_orders!
   end

app/jobs/subscription_placement_job.rb

@@ -2,7 +2,7 @@
 
 require 'order_management/subscriptions/summarizer'
 
-class SubscriptionPlacementJob < ActiveJob::Base
+class SubscriptionPlacementJob < ApplicationJob
   def perform
     proxy_orders.each do |proxy_order|
       place_order_for(proxy_order)

spec/services/job_processor_spec.rb

@@ -8,7 +8,7 @@ MiniRacer::Platform.set_flags!(:single_threaded)
 
 require 'spec_helper'
 
-class TestJob < ActiveJob::Base
+class TestJob < ApplicationJob
   def initialize
     @file = Tempfile.new("test-job-result")
     super