A more flexible Mock 👩🏽‍🔬

From now on testing with a NetworkServiceMock is more flexible.
It allows you to test cases where multiple requests are involved.

• When your code performs multiple requests, NetworkServiceMock now queues them and you are able to respond to all requests independently with success or error.
• Request chains are now supported: Requests started by responses of requests started by responses of requests started by responses... 🌀