Setting network mode to host.
Enables testing without additional configuration of the host.

Change-Id: I46406d414290ed785a4644c88cbc76ff074e96a2

This change bumps up the maximum supported Ansible version to 4.x
(ansible-core 2.11.x) and minimum to 2.10. This synchronises Kayobe with
Kolla Ansible (see change I8b9212934dfab3831986e8db55671baee32f4bbd).

Uses of docker_image are updated. We must now provide the source
parameter. When source is build (for molecule), we replace force by
force_source and force_tag and move path and dockerfile under the build
parameter.

Use docker_image_info instead of docker_image_facts.

Handle update of ansible inside kolla-ansible virtualenv and document
how to do it for the kayobe virtualenv.

Change-Id: I7a4530f4f63ddb37aa30a617db5944b97bc3e17f

Molecule also needs to be bumped to support Ansible 2.10
lint: section changed in Molecule 3.x - adapted.
molecule-docker added do test-reqs because it code has moved to it from
molecule core
pytest-testinfra and pytest-molecule needed for testinfra tests to work

[1]: https://github.com/ansible-community/molecule/issues/2872

Change-Id: I0299f5126ebd080f3912a76294b0013abe7747a0

This scenario enables all services, and checks that expected
configuration files are generated. More validation of configuration file
contents could be added in future.

Tests operation of the role with default variable values.