This patch adds a molecule configuration file at the repository
level (tripleo-validations/.config/molecule/config.yml) which defines
all the default values for molecule.yml files in all roles.
This patch also introduces a common Dockerfile (UBI8 image) shared
between all the role molecule tests. This Dockerfile will install the
CentOS 8.x Linux Repos and GPG Keys during the image build.
This Dockerfile is located in tripleo-validations/.config/molecule
directory and it is shared through a relative symbolic link between all
the molecule directories.
NOTE: tox-ansible doesn't manage shared molecule configuration at the
project level (see ). To be able to use it, we have to explicitly add
the driver name in each molecule.yml file in the roles level. Once 
will be fixed, these will be removed.
 - https://github.com/ansible-community/tox-ansible/issues/88).
Signed-off-by: Gael Chamoulaud (Strider) <firstname.lastname@example.org>
(cherry picked from commit