Move roles/matrix* to roles/custom/matrix*

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.

roles/custom/matrix-postgres/templates/systemd/matrix-postgres.service.j2

@@ -0,0 +1,46 @@
+#jinja2: lstrip_blocks: "True"
+[Unit]
+Description=Matrix Postgres server
+After=docker.service
+Requires=docker.service
+DefaultDependencies=no
+
+[Service]
+Type=simple
+Environment="HOME={{ matrix_systemd_unit_home_path }}"
+ExecStartPre=-{{ matrix_host_command_sh }} -c '{{ matrix_host_command_docker }} kill matrix-postgres 2>/dev/null || true'
+ExecStartPre=-{{ matrix_host_command_sh }} -c '{{ matrix_host_command_docker }} rm matrix-postgres 2>/dev/null || true'
+
+# We need /dev/shm to be larger than the default to allow VACUUM to work.
+# See:
+# - https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1362
+# - https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1268
+ExecStart={{ matrix_host_command_docker }} run --rm --name matrix-postgres \
+			--log-driver=none \
+			--user={{ matrix_user_uid }}:{{ matrix_user_gid }} \
+			--cap-drop=ALL \
+			--read-only \
+			--tmpfs=/tmp:rw,noexec,nosuid,size=100m \
+			--tmpfs=/run/postgresql:rw,noexec,nosuid,size=100m \
+			--shm-size=256m \
+			--network={{ matrix_docker_network }} \
+			{% if matrix_postgres_container_postgres_bind_port %}
+			-p {{ matrix_postgres_container_postgres_bind_port }}:5432 \
+			{% endif %}
+			--env-file={{ matrix_postgres_base_path }}/env-postgres-server \
+			--mount type=bind,src={{ matrix_postgres_data_path }},dst=/var/lib/postgresql/data \
+			--mount type=bind,src=/etc/passwd,dst=/etc/passwd,ro \
+			{% for arg in matrix_postgres_container_extra_arguments %}
+			{{ arg }} \
+			{% endfor %}
+			{{ matrix_postgres_docker_image_to_use }} \
+			postgres {{ matrix_postgres_process_extra_arguments|join(' ') }}
+
+ExecStop=-{{ matrix_host_command_sh }} -c '{{ matrix_host_command_docker }} kill matrix-postgres 2>/dev/null || true'
+ExecStop=-{{ matrix_host_command_sh }} -c '{{ matrix_host_command_docker }} rm matrix-postgres 2>/dev/null || true'
+Restart=always
+RestartSec=30
+SyslogIdentifier=matrix-postgres
+
+[Install]
+WantedBy=multi-user.target