Option to give parameter values for Yii::t as a Closure.

```php
public function rules() {
    return [
        [
            'item_name',
            'unique',
            'targetAttribute' => [ 'item_name' ],
            'filter' => function ( $query ) {

                /** @var \yii\db\Query $query */
                // Check for complex Primary Key [item_name, user_id]
                $query->andWhere( [ 'user_id' => $this->user_id ] );
            },
            'message' => Yii::t('application',
                'Specified auth item "{value}" already assigned for user "{login}".',
                [
                    'login' => function () { return $this->user->login; },
                    'name' => $this->item_name
                ]
            )
	]
    ];
}