Adding internal legacy identifiers (of media and editorial objects) in the knowledge graph

[rtroncy]

The internal legacy identifiers from Yle and INA need to be preserved in the knowledge graph. @Siliam what is the RDF property used for this?

This concerns first class object such as:

• http://data.memad.eu/media/[UUID]
• http://data.memad.eu/[source|channel]/[collection|timeslot|series]/[UUID]