Support multiple topic modelling sets

[theorm]

At the moment a single topics scores set can be added to a resource. We want to be able to add multiple sets. This will help us compare scores sets created using different models. If more than one set is associated with a resource we should be able to select the working set in a dropdown list. The set ID should be reflected in the URL for navigation/deeplinking.

[lwieneke]

Prio 2

As we don't have other topic scores yet. In principle we could also integrate this in the same mechanism as #8