No event is fired if metaobject of an entry/node is saved

Description

The fix for COM-3914 (Updating catalog content causes unnecessary database roundtrips) has the side effect that events (from EventContext, CatalogEventBroadcaster and CatalogEventHandler) aren't raised as often as before. COM-5375 (Don't raise update events for unmodified DTO rows) might have reduced events even further.

This amplifies an underlying problem in the event system: Events are not raised for actions that only change meta data and not the entry/node base data. For example, if an overwrite import changes only an entry's meta fields, no event is raised for that entry. Updating only meta data through the Content Repository or in the Catalog UI still triggered events. However, another bug was causing the base node/entry data to be marked as changed even though there was no actual change.

Find's incremental indexing depends on these events. So, you could have a situation where you import changes to the catalog but the index isn't updated. Or, other custom event handlers are not triggered. The events should be raised for meta data changes as well to make sure this works.