Supersedes https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2472

With this, other roles (like Coturn, Postmoogle) will be able
to use SSL certificates extracted from Traefik
via https://github.com/ldez/traefik-certs-dumper

This gets us started on adding a Traefik role and hooking Traefik:

- directly to services which support Traefik - we only have a few of
  these right now, but the list will grow

- to matrix-nginx-proxy for most services that integrate with
  matrix-nginx-proxy right now

Traefik usage should be disabled by default for now and nothing should
change for people just yet.

Enabling these experiments requires additional configuration like this:

```yaml
devture_traefik_ssl_email_address: '.....'

matrix_playbook_traefik_role_enabled: true
matrix_playbook_traefik_labels_enabled: true

matrix_ssl_retrieval_method: none

matrix_nginx_proxy_https_enabled: false

matrix_nginx_proxy_container_http_host_bind_port: ''
matrix_nginx_proxy_container_federation_host_bind_port: ''

matrix_nginx_proxy_trust_forwarded_proto: true

matrix_nginx_proxy_x_forwarded_for: '$proxy_add_x_forwarded_for'

matrix_coturn_enabled: false
```

What currently works is:
reverse-proxying for all nginx-proxy based services **except** for the Matrix homeserver
(both Client-Server an Federation traffic for the homeserver don't work yet)

Related to https://github.com/devture/com.devture.ansible.role.timesync

The new version uses the corresponding container image when running
vacuum, not the latest Postgres version.

This role is usable on its own and it's not tied to Matrix, so
extracting it out into an independent role that we install via
ansible-galaxy makes sense.

This also fixes the confusion from the other day, where
`matrix_postgres_*` had to be renamed to `devture_postgres_*`
(unless it was about `matrix_postgres_backup_*`).
We now can safely say that ALL `matrix_postgres_*` variables need to be
renamed.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2305