Currently, `org.jgroups.tests.Probe` class does all the heavy lifting and has all the infrastructure needed to contact a cluster to retrieve metrics/status/perform managed operations. This opens the possibility of utilizing `Probe` as a client API to develop custom scripts that require access to the cluster nodes.

One existing limitation is that `Probe` automatically redirects the response to the standard output. To have more flexibility using it to develop the client side, we need an API to register a custom response handler, so instead of writing to standard output, the response is passed to the user's handler.

Ideally, this custom handler should receive the `Address` of which node sent the response, and the `ByteArray` payload, with the actual response. If the custom handler is installed, nothing is written to standard output.