This commit adds copyright attributions in SPDX to the files for matrix-client-cinny, following REUSE's specification.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

This:

- brings consistency - no more mixing `_name_prefix` and `_registry_prefix`
- adds extensibility - a future patch will allow reconfiguring all registry prefixes for all roles in the playbook

We still have `_docker_` vs `_container_` inconsistencies.
These may be worked on later.

This is done for a few reasons:

- less globals and more indepdendence for each role is better. We rely
  on various externally-hosted roles and they don't rely on this global
  either.

- `matrix_container_global_registry_prefix` could make people think they
  could just override this variable and have all their images pull from
  elsewhere. This is rarely the case, unless you've taken special care
  to mirror all the various components (from their respective
  registries) to your own. In such a case, you probably know what you're
  mirroring and can adjust individual variables.

- nowadays, various components live on different registries.
  With Docker Inc tightening rate limits for Docker Hub, it's even more
  likely that we'll see increased diversity in where images are hosted

Provoked by https://github.com/etkecc/mrs/pull/4
I've discovered that Cinny supports various configuration options and it'd be better
if we add support for them.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

Cinny includes nginx configuration which does URL rewrites now, as seen
here: https://raw.githubusercontent.com/cinnyapp/cinny/dev/docker-nginx.conf

That said, we have our own nginx configuration for Cinny, because we'd
like to run ngin as non-root and on a non-privileged port (80 -> 8080).

For this reason, we override `/etc/nginx/nginx.conf` and need to
duplicate what we see in `/etc/nginx/conf.d/default.conf` with our own
`server` block (which listens on port 8080).

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.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/3333

Putting each client into its own network was good for isolation,
but it's quite wasteful in terms of the container network pool.

`always` is an nginx suffix, which shouldn't have been added to these.

Previously, it had to go through matrix-nginx-proxy.
It's exposed to Traefik directly via container labels now

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.