Move items into consolidated properties

[defagos]

As a developer integrating Pillabox I want to be able to listen to consistent state information (introduced in #559). This is currently not the case with items stored within the player.

Acceptance criteria

• Player items have been consolidated in player properties (if meaningful).

Tasks

• Consolidate properties by adding stored items as well if this makes sense.
• Even if the above does not make sense, consolidate Control Center publishers so that they all emerge from the same item update stream.

[defagos]

I consolidate item change updates in a way similar to how we consolidate properties. For the rest the implementation is likely good enough.