Support datetime string for `CookieLogin` duration

See https://github.com/yiisoft/user/blob/master/config/di-web.php#L38

```php

($duration = $params['yiisoft/user']['cookieLogin']['duration']) !== null ?
                (
                    str_starts_with($duration, 'P') ?
                    new DateInterval($duration) : 
                    DateInterval::createFromDateString($duration)
                ) :
                null,
```