Annotation of containers created by pman

[jennydaman]

pman should annotate the containers it creates (on Kubernetes or Docker Swarm) so that the container engine can be queried for information about currently existing containers created by ChRIS. Such a feature would enable telemetry about container runtime information, e.g. "what is the peak memory usage of ChRIS plugins?"

[sakshi1215]

@jennydaman #218 To get the per plugins metrics we need to expose metrics at some pod, I can write a small prometheus server which can expose all these details from the container.

[jennydaman]

#223 added a new setting JOB_LABELS which is currently supported by CONTAINER_ENV=docker