This adds some of the sections from the service template that are
ansible-related:
* host_prep_tasks
* deploy_steps_tasks
* external_deploy_tasks
While this list in not exhaustive (yet), it covers the most important
ones for folks to build their services.
More patches are coming to describe the rest of the parameters.
Change-Id: I207aeae6d425adbcfb04f7df2ad1e73e6f059706
Related-Bug: #1804642
1d5e72b84e