add docker cleanup helpers

[shadeofblue]

In order to simplify goth usage, we may wish to include the commands that we execute in github workflows as helper scripts in the goth repository:

e.g.: Disconnect Docker containers from default network:

docker network inspect docker_default
docker network inspect docker_default | jq ".[0].Containers | map(.Name)[]" | tee /dev/stderr | xargs --max-args 1 -- docker network disconnect -f docker_default

• requires jq to be added to project's os dependencies