subtests.docker_cli: Add detach and interaction test

This pull request implements the https://github.com/autotest/autotest-docker/pull/192 inside the test instead of framework to give it time to stabilize before turning it into framework. I believe that this implementation is cleaner and easier to follow than hybrid implementation from https://github.com/autotest/autotest-docker/pull/194

Kind regards,
Lukáš
``functools.partial()`` does basically this, though unless there's a good reason (I haven't seen below yet) using them is typically considered bad-form.  The main problem is they hide behavior so well that the code becomes increasingly difficult to understand, maintain, and extend over time.  But that's not just ready-made advice, I have first experience with these negative aspects, including the full-brunt of the headaches they can cause later on.  Though I'll keep an open mind, as I read on...