Re-index items which use an item that is updated

Current situation

When updating (for example) a keyword title, the taxonomy filters are not updated

Required situation

When updating a content item all items which use it should be added to the indexation queue

Technical approach

Event listener to query relations.references.$id for the current document. Add all requests to the Solr queue. Note: for performance reasons there will be a hardcoded limit in number of items that will be queued, until we have a system to move this process to the background. At this time the process may take 20 seconds as a maximum. Installations with a large number of link to items may require a manual reindex after updating a heavy used item.