Import Ansible configurations to ocaml/infrastructure

[tmattio]

Tarides has been working on automating the deployment of the OCaml services (inclusive of opam-repo-ci, ocaml-docs-ci, docker-base-images, etc.) through Ansible scripts.

We'd like to make these Ansible configurations publicly available at ocaml/infrastructure to make the maintenance of the OCaml infrastructure more transparent and ultimately allow the community to contribute.