Issue #3362297 Provide new configuration option in the Registrant Settings form to enable/disabled the email notifications queue

• New option in the Registrant form (/admin/structure/events/registrant/settings) to enable/disable the email notifications queue:
• If enabled, the email notifications corresponding to the types below will be queued, otherwise they will be sent immediately: -- Instance Deletion Notification -- Series Deletion Notification -- Instance Modification Notification -- Series Modification Notification -- Registration Reminder

modules/recurring_events_registration/config/schema/recurring_events_registration.schema.yml

@@ -26,6 +26,9 @@ recurring_events_registration.registrant.config:
     email_notifications:
       type: boolean
       label: 'Whether to enable email notifications'
+    email_notifications_queue:
+      type: boolean
+      label: 'Whether to use the email notifications queue'
     notifications:
       type: sequence
       sequence: