add ck editor file upload endpoint

app/models/ck_editor_upload.rb

@@ -0,0 +1,11 @@
+# == Schema Information
+#
+# Table name: ck_editor_uploads
+#
+#  id         :bigint           not null, primary key
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+class CkEditorUpload < ApplicationRecord
+  has_one_attached :attachment
+end