Allow scraping the installed collections on Tower nodes

[ansiblejunky]

Currently the repo handles python modules, pip, etc. Would be great to have it also scrape existing installed Ansible Collections on the Tower nodes (collection name and version). This would be added to the final output of the playbook. For example, customer has collections installed in a custom path on the Tower nodes (/app/collections) which is set in the /etc/ansibe/ansible.cfg configuration file. Also note that, since Tower uses Ansible 2.9 the ansible-galaxy collection list command is not available.

Would be nice to add this feature.