Feature request: Support to throw an RequestException

[aalwash]

First of all, thank you for this amazing package!
Love the additional assertions you can do on top of the guzzle handler stack!

With the current Guzzle handler you're allowed to set a RequestException in the handler stack

Would be nice to have some functionality to support this in the current package.

See original Guzzle docs and look for https://docs.guzzlephp.org/en/stable/testing.html

[aalwash]

It's already possible.
If you don't "care" much about the assertion, you just want to throw an exception on a specific request, you use something like this

      (new GuzzleMockResponse('random-path'))
                    ->withBody(['status' => 'running'])
                    ->withStatus(SymfonyResponse::HTTP_OK)
                    ->withAssertion(function() {
                        throw new ConnectException('Empty server reply', new Request('GET', '/random-path'));
                    })
                    ->once(),