FIX: Only show "Approve" button for the admin user if reviewable

app/serializers/admin_user_serializer.rb

@@ -7,11 +7,21 @@ class AdminUserSerializer < AdminUserListSerializer
              :can_send_activation_email,
              :can_activate,
              :can_deactivate,
+             :can_approve,
              :ip_address,
              :registration_ip_address
 
   has_one :single_sign_on_record, serializer: SingleSignOnRecordSerializer, embed: :objects
 
+  def can_approve
+    reviewable = ReviewableUser.find_by(target: object)
+    reviewable.present? && reviewable.actions_for(scope).has?(:approve)
+  end
+
+  def include_can_approve?
+    SiteSetting.must_approve_users
+  end
+
   def can_send_activation_email
     scope.can_send_activation_email?(object)
   end