Validation errors for haveRecord method

When haveRecord is used and it fails to create a model due to some validation, it's not obvious from the test output why.
The proposed fix will append default failure message with associated validation errors

Author: ianikanov

src/Codeception/Module/Yii2.php

@@ -574,7 +574,7 @@ public function haveRecord($model, $attributes = [])
         $record->setAttributes($attributes, false);
         $res = $record->save(false);
         if (!$res) {
-            $this->fail("Record $model was not saved");
+            $this->fail("Record $model was not saved: " . \yii\helpers\Json::encode($record->errors));
         }
         return $record->primaryKey;
     }