Review Changelog Active Record Key

There are four changelog metadata attributes. Three have fixed names: actor_identifier, deleted, and revision. The fourth is dynamically constructed from the name of the table, eg email_addresses:email_address_id is the changelog active record key, that (when not null) points to the active record that created the archive record. This complicates code since the attribute name must be dynamically constructed, even though its function doesn't change.

Consider renaming this key something like "active_record_id".

If this change is accepted transmogrification will need to be updated.