Allow the `WWW-Authenticate` header field in other response than 401.

Passing `WWW-Authenticate` to `header()` overwrites the status code to 401.

https://github.com/php/php-src/blob/a51cb393b1accc29200e8f57ef867a6a47b2564f/ain/SAPI.c#L829

According to RFC it is said that it is also possible to include `WWW-Authenticate` in status codes other than 401.

https://tools.ietf.org/html/rfc7235#page-7

> A server MAY generate a WWW-Authenticate header field in other response.

Since OAuth 2.0 Bearer writes its contents in `WWW-Authenticate` header even for errors other than 401, the original status code is applied after the status code reaches 401 by inserting the `WWW-Authenticate` header field is necessary.

https://tools.ietf.org/html/rfc6750#page-9
<?php
/**
 * This file is part of the BEAR.Sunday package.
 *
 * @license http://opensource.org/licenses/MIT MIT
 */
namespace BEAR\Sunday\Provide\Transfer;

use BEAR\Resource\ResourceObject;
use BEAR\Sunday\Extension\Transfer\TransferInterface;

class HttpResponder implements TransferInterface
{
    /**
     * {@inheritdoc}
     */
    public function __invoke(ResourceObject $resourceObject, array $server)
    {
        unset($server);
        // render
        if (! $resourceObject->view) {
            $resourceObject->toString();
        }

        // header
        foreach ($resourceObject->headers as $label => $value) {
            header("{$label}: {$value}", false);
        }

        // code
        http_response_code($resourceObject->code);

        // body
        echo $resourceObject->view;
    }
}

<?php
/**
 * This file is part of the BEAR.Sunday package.
 *
 * @license http://opensource.org/licenses/MIT MIT
 */
namespace BEAR\Sunday\Provide\Transfer;

use BEAR\Resource\ResourceObject;
use BEAR\Sunday\Extension\Transfer\TransferInterface;

class HttpResponder implements TransferInterface
{
    /**
     * {@inheritdoc}
     */
    public function __invoke(ResourceObject $resourceObject, array $server)
    {
        unset($server);
        // render
        if (! $resourceObject->view) {
            $resourceObject->toString();
        }

        // code
        http_response_code($resourceObject->code);

        // header
        foreach ($resourceObject->headers as $label => $value) {
            header("{$label}: {$value}", false);
        }

        // body
        echo $resourceObject->view;
    }
}
