Retrieve the scheduled database event consistency of a specific cluster

Scheduled database events (MySQL/MariaDB EVENT objects) as the last schema scan collected them on the master and the replicas (monitoring-schema-events), compared with the master: per server the collection state (checked, unavailable, unsupported, not-checked) and, for a replica, the comparison (consistent, different, not-checked); per event its presence, status class (active, disabled, unknown) and definition CRC64 on each checked server, and its drifts (missing, extra, definition, definer, status). A server absent from an event's nodes was not checked: it is never reported missing. It never carries an event definition, schedule, comment or definer. Observational only: the schema drift signal is WARN0164. enabled is false, with no server and no event, when monitoring-schema-events is off. Requires db-show-schema (or cluster-sharding, through /schema).