Add and apply Style/AccessorGrouping rubocop rule

This rule was added in Rubocop 0.87.0. We were already grouping
accessors in most places.

.rubocop.yml

@@ -368,6 +368,9 @@ Security/JSONLoad:
 Security/YAMLLoad:
   Enabled: true
 
+Style/AccessorGrouping:
+  Enabled: true
+
 Style/AndOr:
   Enabled: true
 

app/models/user.rb

@@ -89,9 +89,7 @@ class User < ApplicationRecord
 
   accepts_nested_attributes_for :organization, update_only: true
 
-  attr_accessor :skip_password_validation
-  attr_accessor :use_redeemable_code
-  attr_accessor :login
+  attr_accessor :skip_password_validation, :use_redeemable_code, :login
 
   scope :administrators, -> { joins(:administrator) }
   scope :moderators,     -> { joins(:moderator) }

app/models/verification/management/email.rb

@@ -1,9 +1,7 @@
 class Verification::Management::Email
   include ActiveModel::Model
 
-  attr_accessor :document_type
-  attr_accessor :document_number
-  attr_accessor :email
+  attr_accessor :document_type, :document_number, :email
 
   validates :document_type, :document_number, :email, presence: true
   validates :email, format: { with: Devise.email_regexp }, allow_blank: true