Availability to install as ansible collection

Will be useful to install acides.hepto as ansible galaxy role.

(See reference : https://docs.ansible.com/ansible/latest/collections_guide/collections_installing.html#specifying-the-collection-location-within-the-git-repository)

• Init a galaxy.yml
• Move playbooks inside /ansible/playbooks (https://docs.ansible.com/ansible/latest/dev_guide/developing_collections_structure.html#playbooks-directory)
• Move needed group_vars to ./roles/{roles}/defaults/
• Update documentations to reflect changes