This change adds a new output to service definitions called
core_services which are used to define task-core services that will be
collected and exported during the config-download progress. These
services are mapped to TripleO roles and published into a task-core role
file in the config-download.
Related-Blueprint: unified-orchestration
Change-Id: I6954ecc92e740212a4502ac5fa8e53eeed22d043
Depends-On: https://review.opendev.org/c/openstack/tripleo-common/+/798721
6d80912404