add matrix_synapse_oidc_enabled and matrix_synapse_oidc_providers vars

roles/custom/matrix-synapse/defaults/main.yml

@@ -425,6 +425,11 @@ matrix_synapse_federation_port_openid_resource_required: false
 # result, it's better to accomplish it by changing `matrix_synapse_federation_enabled`.
 matrix_synapse_federation_domain_whitelist: ~
 
+# Enable/disable OpenID Connect
+matrix_synapse_oidc_enabled: false
+# List of OpenID Connect providers, ref: https://matrix-org.github.io/synapse/latest/openid.html#sample-configs
+matrix_synapse_oidc_providers: []
+
 # A list of additional "volumes" to mount in the container.
 # This list gets populated dynamically based on Synapse extensions that have been enabled.
 # Contains definition objects like this: `{"src": "/outside", "dst": "/inside", "options": "rw|ro|slave|.."}