Invoke webhook when Keycloak-managed user data is updated

For user account deletions and updates, we have Keycloak proactively syncing via a webhook implemented at https://gitlab.com/drupal-infrastructure/sso/drupal-7-extension-helper/-...

This is a synchronous action, so adding more sites would delay the UI in Keycloak. We do need to sync events in a timely manner, especially for deletes to maintain a good privacy/GDPR stance.

drupalorg’s webhook processor, drupalorg_keycloak_event_process() will need to invoke the webhooks for localize.drupal.org, jobs.drupal.org, and any others. The webhook receiver will be in drupalorg_crosssite.

We can implement this now to remove some of the remainders of bakery module, although it will remain to support groups.drupal.org until that site is retired. Or we can wait for more to move to modern Drupal versions to avoid re-implementation.