Add support for running dimension in an unfederated environment

This config change follows:

  https://github.com/turt2live/matrix-dimension/blob/master/docs/unfederated.md

roles/matrix-synapse/templates/synapse/homeserver.yaml.j2

@@ -226,7 +226,11 @@ listeners:
     x_forwarded: true
 
     resources:
-      - names: [client]
+      - names:
+        - client
+{% if matrix_dimension_enabled and not matrix_synapse_federation_enabled %}
+        - openid
+{% endif %}
         compress: false
 
 {% if matrix_synapse_federation_enabled %}