Add the possibility to pass extra flags to the docker container

roles/matrix-mxisd/defaults/main.yml

@@ -8,6 +8,9 @@ matrix_mxisd_data_path: "{{ matrix_mxisd_base_path }}/data"
 # Controls whether the mxisd web server's port (`8090`) is exposed outside of the container.
 matrix_mxisd_container_expose_port: false
 
+# A list of extra arguments to pass to the container
+matrix_mxisd_container_extra_arguments: []
+
 # List of systemd services that matrix-mxisd.service depends on
 matrix_mxisd_systemd_required_services_list: ['docker.service']