Add Ansible integration feature

[pablomh]

Summary

• Register ansible feature in features.yaml with foreman_ansible (Foreman),
  ansible (proxy), and foreman_ansible (Hammer CLI) plugins
• Add smart proxy settings template for the ansible plugin
• Enable ansible by default in the katello flavor
• Depends on remote-execution (which transitively enables dynflow)
• Rename test_foreman_compute_resources to test_foreman_plugin_loaded since
  the parametrized list now includes non-compute plugins

Scope

Ansible is enabled by default in the katello flavor only, matching how other
plugins (katello, remote-execution, rh-cloud) are scoped. Vanilla Foreman installs
can opt in via --add-feature=ansible.

Assumptions

This PR registers the plugin and enables it in the container images. It assumes:

• The Foreman and Smart Proxy container images already ship foreman_ansible and
  smart_proxy_ansible gems
• ansible-core is present in the proxy container image
• SSH key distribution and inventory are handled by REX (dependency)

Test plan

• foreman_ansible plugin loaded in Foreman (API check)
• ansible feature exposed on smart proxy /features endpoint
• "Run Command - Ansible Default" job template seeded
• ansible listed in foremanctl features
• Ansible-based REX job execution against a registered host

🤖 Generated with Claude Code

[pablomh]

Dup of #444 :/