ACTS-412_allowCustomSorting

This merge request depends on !383 (merged) and !387 (merged) and should be merged afterwards. Fixes ACTS-412. With this MR more flexibility is added to the DD4hep translation. It allows the users to implement their own function to sort sub detectors (which was done by ID until now). Furthermore some splitting of functions was done to make the translation more modular, in case a user does not want to use the general convertDD4hepDetector method, but just wants to use some sub methods. This can be usefull in the future, in case some detector parts should not be translated.