Add logging of admin actions (#5757)

* Add logging of admin actions

* Update brakeman whitelist

* Log creates, updates and destroys with history of changes

* i18n: Update Polish translation (#5782)

Signed-off-by: Marcin Mikołajczak <me@m4sk.in>

* Split admin navigation into moderation and administration

* Redesign audit log page

* 🇵🇱 (#5795)

* Add color coding to audit log

* Change dismiss->resolve, log all outcomes of report as resolve

* Update terminology (e-mail blacklist) (#5796)

* Update terminology (e-mail blacklist)

imho looks better

* Update en.yml

* Fix code style issues

* i18n-tasks normalize

app/models/admin/action_log.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: admin_action_logs
+#
+#  id               :integer          not null, primary key
+#  account_id       :integer
+#  action           :string           default(""), not null
+#  target_type      :string
+#  target_id        :integer
+#  recorded_changes :text             default(""), not null
+#  created_at       :datetime         not null
+#  updated_at       :datetime         not null
+#
+
+class Admin::ActionLog < ApplicationRecord
+  serialize :recorded_changes
+
+  belongs_to :account, required: true
+  belongs_to :target, required: true, polymorphic: true
+
+  default_scope -> { order('id desc') }
+
+  def action
+    super.to_sym
+  end
+
+  before_validation :set_changes
+
+  private
+
+  def set_changes
+    case action
+    when :destroy, :create
+      self.recorded_changes = target.attributes
+    when :update, :promote, :demote
+      self.recorded_changes = target.previous_changes
+    end
+  end
+end