dumper: explore running as a Kubernetes ephemeral container

[ivanyu]

Current challenges

1. How to attach the ephemeral debug container to a running pod with PID namespace sharing? It seems K8s allows this only with a copy of the target pod, which doesn't make sense if you want a heap dump.

Experiment notes:

1. Run eval $(minikube docker-env) and build the necessary Docker images on minikube's Docker instead of the host Docker if the images you need can't be pulled from the registry.