Add support for controlling Matrix federation

roles/matrix-server/templates/systemd/matrix-synapse.service.j2

@@ -29,7 +29,9 @@ ExecStart=/usr/bin/docker run --rm --name matrix-synapse \
 			--log-driver=none \
 			--env-file={{ matrix_environment_variables_data_path }}/synapse \
 			--network={{ matrix_docker_network }} \
+			{% if matrix_synapse_federation_enabled %}
 			-p 8448:8448 \
+			{% endif %}
 			{% if not matrix_nginx_proxy_enabled %}
 			-p 127.0.0.1:8008:8008 \
 			{% endif %}