Our page event state modeling includes page_title and a namespace_id fields. However, which namespace contains 'content' may different across wikis.

It would be useful for consumers of mediawiki.page_change.v1 to easily determine if the event is related to a change to a content namespace.

This would be helpful for T403660: WE3.3.7 Year in Review and Activity Tab Services - Global Editor Metrics, where we'd like to allow metric API users to filter pageviews on the type of page.

We could do this by adding page_type enum field, or a boolean is_content_namespace field. Field model and name to be bikeshed.

See: relevant slack thread.

Done is

• it is possible to determine if a page referenced in an event is a content or non content page.
• all event streams that use the fragment/mediawiki/state/change/page schema are updated to include and set this information.