This patch add a way to choose container engine inside tool and test
scripts. This is in preparation for Podman introduction but still
leaves Docker as default container engine.

Signed-off-by: Martin Hiner <m.hiner@partner.samsung.com>
Change-Id: I395d2bdb0dfb4b325b6ad197c8893c8a0f768324

Installs Tenks [1] and uses it to create virtual machines to pose
as bare metal compute nodes.
The nodes are registered in Ironic, and used to provision
instances.

[1] https://docs.openstack.org/tenks/latest/

Depends-On: https://review.opendev.org/c/openstack/tenks/+/830182
Depends-On: https://review.opendev.org/c/openstack/tenks/+/830675
Depends-On: https://review.opendev.org/c/openstack/kolla-ansible/+/831055


Change-Id: Idfb8fbb50dc7442225967b2a2ec38ae7114f3c11
Co-Authored-By: Radosław Piliszek <radoslaw.piliszek@gmail.com>