Add management of delivery availability in Federation settings (#15771)

* Add management of delivery availavility in Federation settings

* fix translate

* Remove useless object creation

* Fix DeepSource issue

* Add shortcut for all

* Fix DeepSource(skipcq)

* Change 'remove' to 'clear'

* Fix style

* Change class method name (exhausted_deliveries_key_by)

app/models/instance.rb

@@ -10,10 +10,13 @@
 class Instance < ApplicationRecord
   self.primary_key = :domain
 
+  attr_accessor :failure_days
+
   has_many :accounts, foreign_key: :domain, primary_key: :domain
 
   belongs_to :domain_block, foreign_key: :domain, primary_key: :domain
   belongs_to :domain_allow, foreign_key: :domain, primary_key: :domain
+  belongs_to :unavailable_domain, foreign_key: :domain, primary_key: :domain # skipcq: RB-RL1031
 
   scope :matches_domain, ->(value) { where(arel_table[:domain].matches("%#{value}%")) }