Move mautrix telegram and whatsapp into separate roles

The goal is to move each bridge into its own separate role.
This commit starts off the work on this with 2 bridges:
- mautrix-telegram
- mautrix-whatsapp

Each bridge's role (including these 2) is meant to:

- depend only on the matrix-base role

- integrate nicely with the matrix-synapse role (if available)

- integrate nicely with the matrix-nginx-proxy role (if available and if
required). mautrix-telegram bridge benefits from integrating with
it.

- not break if matrix-synapse or matrix-nginx-proxy are not used at all

This has been provoked by #174 (Github Issue).

roles/matrix-bridge-mautrix-telegram/templates/systemd/matrix-mautrix-telegram.service.j2

@@ -0,0 +1,45 @@
+#jinja2: lstrip_blocks: "True"
+[Unit]
+Description=Matrix Mautrix Telegram server
+{% for service in matrix_mautrix_telegram_systemd_required_services_list %}
+Requires={{ service }}
+After={{ service }}
+{% endfor %}
+{% for service in matrix_mautrix_telegram_systemd_wanted_services_list %}
+Wants={{ service }}
+{% endfor %}
+
+[Service]
+Type=simple
+ExecStartPre=-/usr/bin/docker kill matrix-mautrix-telegram
+ExecStartPre=-/usr/bin/docker rm matrix-mautrix-telegram
+ExecStartPre=/usr/bin/docker run --rm --name matrix-mautrix-telegram-db \
+			--log-driver=none \
+			--user={{ matrix_user_uid }}:{{ matrix_user_gid }} \
+			--cap-drop=ALL \
+			-v {{ matrix_mautrix_telegram_base_path }}:/data:z \
+			{{ matrix_mautrix_telegram_docker_image }} \
+			alembic -x config=/data/config.yaml upgrade head
+
+ExecStart=/usr/bin/docker run --rm --name matrix-mautrix-telegram \
+			--log-driver=none \
+			--user={{ matrix_user_uid }}:{{ matrix_user_gid }} \
+			--cap-drop=ALL \
+			--network={{ matrix_docker_network }} \
+			{% if matrix_mautrix_telegram_container_exposed_port_number is not none %}
+			-p 127.0.0.1:{{ matrix_mautrix_telegram_container_exposed_port_number }}:8080 \
+			{% endif %}
+			-v {{ matrix_mautrix_telegram_base_path }}:/data:z \
+			{% for arg in matrix_mautrix_telegram_container_extra_arguments %}
+			{{ arg }} \
+			{% endfor %}
+			{{ matrix_mautrix_telegram_docker_image }} \
+			python3 -m mautrix_telegram -c /data/config.yaml
+
+ExecStop=-/usr/bin/docker kill matrix-mautrix-telegram
+ExecStop=-/usr/bin/docker rm matrix-mautrix-telegram
+Restart=always
+RestartSec=30
+
+[Install]
+WantedBy=multi-user.target