Switch to use `docker context`

Description

Switch to use docker context to get access to docker daemon. See https://docs.docker.com/engine/context/working-with-contexts/

This will aid using tools like colima.

I.e. change line: https://gitlab.developers.cam.ac.uk/uis/devops/tools/logan/-/blob/master/logan/tool.py?ref_type=heads#L373