use docker package

[donghwan-shin]

@SepShr I found that there are subprocess.run() for running docker commands. Instead, I found that we can use this docker package: https://docker-py.readthedocs.io/en/stable/index.html#.

For example, you can simply get a short ID (of length 12) of a container named 'pylot' as follows:

import docker
client = docker.from_env()
id = client.containers.get('pylot').short_id

Using subprocess.run() and extracting proper information from its output seems fragile. I recommend using the official docker package. :)

[SepShr]

This issue will be closed since the parallel simulation setup uses the docker library extensively in place of shell scripts.