With this change, the existing host-based Ansible provisioner is
refactored to share a maximum of code with this new guest-based Ansible
provisioner.
At this stage of development, the existing unit tests are intentionally
modified as little as possible, to keep safe the existing funtionalities.
Other issues resolved by this changeset:
- Display a warning when running from a Windows host [GH-5292]
- Do not run `ansible-playbook` in verbose mode when the `verbose` option
is set to an empty string.
