Write tests mimicking slow and intermittent network responses

As follow up from discussions, implement some integrations in `azure_core` that mimic slow, chunky network responses where some of those chunks may exhibit a network error. This point is to make sure that - whether calling `Response::into_body()` and streaming the `ResponseBody` or calling `Response::deserialize_body()` - we correctly retry requests.

Note: this is not about ranged request headers e.g., with Storage, but that we at least start over from the beginning and try again for both retriable HTTP status codes as well as network "hiccups".