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
Copying the hierarchy is fine as a starting place, I expect it to diverge over time.  This was mainly just a suggestion for helping this stuff along the path to package inclusion.  If you'd prefer it to just be replaced later, then that's just making more work for yourself or somebody else.  Hence my emphasis on super-duper simple tests.