Move "everyone" role and "instance actor" account magic number IDs to constants (#29260)

db/migrate/20190715164535_add_instance_actor.rb

@@ -5,6 +5,8 @@ class AddInstanceActor < ActiveRecord::Migration[5.2]
     # Dummy class, to make migration possible across version changes
     validates :username, uniqueness: { scope: :domain, case_sensitive: false }
 
+    INSTANCE_ACTOR_ID = -99
+
     before_create :generate_keys
 
     def generate_keys
@@ -15,10 +17,10 @@ class AddInstanceActor < ActiveRecord::Migration[5.2]
   end
 
   def up
-    Account.create!(id: -99, actor_type: 'Application', locked: true, username: Rails.configuration.x.local_domain)
+    Account.create!(id: Account::INSTANCE_ACTOR_ID, actor_type: 'Application', locked: true, username: Rails.configuration.x.local_domain)
   end
 
   def down
-    Account.find_by(id: -99, actor_type: 'Application').destroy!
+    Account.find_by(id: Account::INSTANCE_ACTOR_ID, actor_type: 'Application').destroy!
   end
 end

db/post_migrate/20220704024901_migrate_settings_to_user_roles.rb

@@ -3,7 +3,9 @@
 class MigrateSettingsToUserRoles < ActiveRecord::Migration[6.1]
   disable_ddl_transaction!
 
-  class UserRole < ApplicationRecord; end
+  class UserRole < ApplicationRecord
+    EVERYONE_ROLE_ID = -99
+  end
 
   def up
     process_role_everyone
@@ -17,7 +19,7 @@ class MigrateSettingsToUserRoles < ActiveRecord::Migration[6.1]
   private
 
   def process_role_everyone
-    everyone_role = UserRole.find_by(id: -99)
+    everyone_role = UserRole.find_by(id: UserRole::EVERYONE_ROLE_ID)
     return unless everyone_role
 
     everyone_role.permissions &= ~::UserRole::FLAGS[:invite_users] unless min_invite_role == 'user'

db/seeds/02_instance_actor.rb

@@ -1,3 +1,3 @@
 # frozen_string_literal: true
 
-Account.create_with(actor_type: 'Application', locked: true, username: 'mastodon.internal').find_or_create_by(id: -99)
+Account.create_with(actor_type: 'Application', locked: true, username: 'mastodon.internal').find_or_create_by(id: Account::INSTANCE_ACTOR_ID)