pundit: convert moderation reports to pundit.

app/policies/moderation_report_policy.rb

@@ -0,0 +1,13 @@
+class ModerationReportPolicy < ApplicationPolicy
+  def index?
+    user.is_moderator?
+  end
+
+  def create?
+    unbanned? && policy(record.model).reportable?
+  end
+
+  def permitted_attributes
+    [:model_type, :model_id, :reason]
+  end
+end