With this change, all dependency roles are downloaded
using the same mechanism (git), which makes life simpler for tools like
https://gitlab.com/etke.cc/int/agru

With these changes, we:

- install https://github.com/Tecnativa/docker-socket-proxy via the
  https://github.com/devture/com.devture.ansible.role.container_socket_proxy Ansible role

- make Traefik access the Docker API via TCP by connecting to this
  socket proxy

- .. which allows us to run the Traefik container with less privileges
  (non-`root`, dropped capabilities)

This new role also adds native Traefik support and support for other
(non-`amd64`) architectures via self-building.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2532

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2522