subtests.docker_cli: Add test run_cidfile

Fixes: https://github.com/autotest/autotest-docker/issues/264

This test is focussed on correct handling of `docker run --cidfile`

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Note: Have to be careful with this, if dkrcmd_cls is an async-variety, ``_init_container()`` will probably return **before** the container is actually up an running.  Calling method will need to be careful to always sync. if so.

It looks like you always sync., in the code below, but consider maybe putting above as a comment (or some other protection) to help (possibly) prevent human-error when maintaining or adding on to the test.  An alternative is to simply always sync. before returning, but that could reduce the tests which are possible, not sure if that's important now or not, maybe not.