http client config hooks interface

[Crim]

Provides an interface for modifying how the underlying HttpClient instance is created.

Usage of this would look like:

final RestClient restClient = new HttpClientRestClient(new HttpClientConfigHooks {
    // Override methods as needed to modify behavior.
});

// Create client, passing configuration and RestClient implementation
final KafkaConnectClient client = new KafkaConnectClient(configuration, restClient);

// Use client as normal...

[Crim]

@MosheElisha Please see the above PR. I've added a more maintainable method for being able to override internal setup and configuration of the underlying HttpClient via a new interface.

I believe this should continue to be able to solve your use cases correct? If so I'll merge this and cut a release.

Thanks!

[MosheElisha]

Looks good to me! Thanks!