Related to 0241c71a4c

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3270#issuecomment-2143782962

With this change, it should be possible for people to adjust the Docker
dependency from `docker.service` to something else (e.g. `pkg-ContainerManager-dockerd.service`),
or to completely eliminate it by setting `devture_systemd_docker_base_docker_service_name` to an empty string.

This makes it easier for people to use the playbook against a Synology DSM server.

This is still very far from usable.

Various bridges and bots are still talking to
`matrix-nginx-proxy` instead of the new `matrix-homeserver-proxy` role.
These services need to be reworked. While reworking them,
various cleanups are being done as well as adding Traefik-labels to
those that need them.

This is backward-compatible with what we had before. We're not changing
the SSL mode - just making it configurable.

Most components are defaulting to `sslmode=disable`, while some
(`matrix-bot-matrix-reminder-bot` and others) do not specify an `sslmode` at all.

We're making sslmode configurable, because certain external Postgres
servers may be configured to require SSL encryption.
In such cases `sslmode=disable` does not work and needs to be changed to
`sslmode=require` or something else (`verify-ca`, `verify-full`, etc).

* make banlist consistent
* proper multi-error message
* ignore "." MX hosts
* try recipient domain directly, even when MX records found, but failed

* live SSL certificates reload on file changes (e.g., on automatic certs renewal)
* print all errors when trying connection to an SMTP server

* fix uploads from incoming emails into matrix threads
* fix emails dequeue (account data cleanup)
* rewrite recipients handling (Cc, To, etc.)

This paves the way for installing other roles into `roles/galaxy` using `ansible-galaxy`,
similar to how it's done in:

- https://github.com/spantaleev/gitea-docker-ansible-deploy
- https://github.com/spantaleev/nextcloud-docker-ansible-deploy

In the near future, we'll be removing a lot of the shared role code from here
and using upstream roles for it. Some of the core `matrix-*` roles have
already been extracted out into other reusable roles:

- https://github.com/devture/com.devture.ansible.role.postgres
- https://github.com/devture/com.devture.ansible.role.systemd_docker_base
- https://github.com/devture/com.devture.ansible.role.timesync
- https://github.com/devture/com.devture.ansible.role.vars_preserver
- https://github.com/devture/com.devture.ansible.role.playbook_runtime_messages
- https://github.com/devture/com.devture.ansible.role.playbook_help

We just need to migrate to those.

* fix room account data retrieving

* show recipient's email (header `TO`)
* add `norecipient` option
* add anti-spam options (`spamcheck:` and `spamlist:`)
* fix bugs

* send emails in UTF-8 👋
* fix options descriptions
* add SMTP auth
* allow sending emails from your apps and scripts using postmoogle as email provider

.. instead of `['']`.

The final result in the `env` file will be the same (`POSTMOOGLE_ADMINS=`)
in both cases, but it's better to avoid confusion.

* postmoogle: add admins

* postmoogle: update jija2 defaults

* postmoogle: fix typo

Before this, it was trying to pull the `latest` git branch.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/2043