Extract all content type actions into separate service

The main point of this exercise is to get the remaining Neo4j*Repository instances out of ResourceService. This is important for tests.

Also, the feature for unlisted/featured resources is not working as expected in some cases. This refactors that component to start getting it under test. It removes a lot of duplication. From there, we have a chance to encode the expected behavior into tests and fix remaining issues. I would like to address this later, though, as the changes are quite substantial already.