Solves #3153. It refactors images attributes.

app/controllers/admin/milestones_controller.rb

@@ -1,5 +1,6 @@
 class Admin::MilestonesController < Admin::BaseController
   include Translatable
+  include ImagesHelper
 
   before_action :load_milestoneable, only: [:index, :new, :create, :edit, :update, :destroy]
   before_action :load_milestone, only: [:edit, :update, :destroy]
@@ -41,7 +42,6 @@ class Admin::MilestonesController < Admin::BaseController
   private
 
   def milestone_params
-    image_attributes = [:id, :title, :attachment, :cached_attachment, :user_id, :_destroy]
     documents_attributes = [:id, :title, :attachment, :cached_attachment, :user_id, :_destroy]
     attributes = [:publication_date, :status_id,
                   translation_params(Milestone),

app/controllers/admin/poll/polls_controller.rb

@@ -1,5 +1,6 @@
 class Admin::Poll::PollsController < Admin::Poll::BaseController
   include Translatable
+  include ImagesHelper
   load_and_authorize_resource
 
   before_action :load_search, only: [:search_booths, :search_officers]
@@ -60,7 +61,6 @@ class Admin::Poll::PollsController < Admin::Poll::BaseController
     end
 
     def poll_params
-      image_attributes = [:id, :title, :attachment, :cached_attachment, :user_id, :_destroy]
       attributes = [:name, :starts_at, :ends_at, :geozone_restricted, :results_enabled,
                     :stats_enabled, geozone_ids: [],
                     image_attributes: image_attributes]

app/controllers/admin/widget/cards_controller.rb

@@ -1,5 +1,6 @@
 class Admin::Widget::CardsController < Admin::BaseController
   include Translatable
+  include ImagesHelper
 
   def new
     @card = ::Widget::Card.new(header: header_card?)
@@ -40,8 +41,6 @@ class Admin::Widget::CardsController < Admin::BaseController
   private
 
   def card_params
-    image_attributes = [:id, :title, :attachment, :cached_attachment, :user_id, :_destroy]
-
     params.require(:widget_card).permit(
       :link_url, :button_text, :button_url, :alignment, :header,
       translation_params(Widget::Card),