[11.x] Add ResponseInterface mixin to Illuminate\Http\Client\Response

[einar-hansen]

This PR adds the Psr\Http\Message\ResponseInterface interface as a mixin to the Response class. This will make our IDE completion better.

/**
 * @mixin \Psr\Http\Message\ResponseInterface
 */

The Response class is using the magic __call method and forwards it calls to the $response property, therefore all the methods on the $response property is available for the developer.

    /**
     * The underlying PSR response.
     *
     * @var \Psr\Http\Message\ResponseInterface
     */
    protected $response;

    public function __call($method, $parameters)
    {
        return static::hasMacro($method)
                    ? $this->macroCall($method, $parameters)
                    : $this->response->{$method}(...$parameters);
    }