MediaWiki Tags AKA change tags or revision tags allow MW revisions and log entries to be 'annotated' with extra information after the revision or log entry is created.

This system is most notably used to mark revisions as having been reverted.

There is an existent legacy mediawiki.revision-tags-change event stream, but this stream:

• only captures tags for revisions
• only emits tags added or removed by an event: it does not use our standard state change model. The event does not include the complete list of tags at the time of the event.

We should replace mediawiki.revision-tags-change with a more generic mediawiki.tags_change stream based on MW event entity data models.

Along the way, let's make sure we don't reproduce {T432948}. Either we shouldn't emit private tags, or those should be emitted to a different stream.

Done is

• New mediawiki/tags/change schema
• New mediawiki.tags_change.v1 stream captures state of tag changes
• Optional: mediawiki.revision-tags-change stream is decomissioned. (We may want to do this more holistically for all legacy deprecated MW streams)