Allow selecting executable by used port

[mariomac]

Currently, you can select which executable to instrument by its name. This could lead to some issues in the Kubernetes scenario where deploying as a daemonset is not an option, and you need to deploy as a sidecar. For example, when you have 100 nodes and 10 instances of the service.

In that case, to avoid that a sidecar instruments processes from other pods in the same node, we could configure the instrumenter to listen to e.g. "process listening on port 8080". Since port space is internal to the pod, you can be sure you are instrumenting only the right executable.