Decouple service name from hostname

[ekohl]

Today foreman-installer is unintentionally quite tied to the system's hostname. This necessitates tools like katello-change-hostname. In foremanctl I'd like to decouple it fully, which aligns with a containerized model.

A use cases that I'd like to see work: install on 1 hostname, then change it and keep serving the application on the old.

# hostname
foreman.example.com
# foremanctl deploy
# hostnamectl hostname host12345.example.com
# foremanctl deploy
# curl https://foreman.example.com
valid output here

Another is to install straight away on a different service name:

# hostname
host12345.example.com
# foremanctl deploy --service-name foreman.example.com
# curl https://foreman.example.com
valid output here

The exact parameter name is up for debate.

Today we use the FQDN fact too often and that's IMHO an anti-pattern. For example:

foremanctl/src/vars/base.yaml

Line 3 in 099a9fe

- "{{ ansible_facts['fqdn'] }}"

foremanctl/src/vars/base.yaml

Lines 34 to 35 in 099a9fe

	pulp_content_origin: "https://{{ ansible_facts['fqdn'] }}"
	pulp_pulp_url: "https://{{ ansible_facts['fqdn'] }}"