Draft: Refactoring and clean up to avoid clashes with LHCb

Run2Support is meant to provide the implementation of DetDesc on top of LHCb (built with DD4hep).

Because of the way the switch between DetDesc and DD4hep in LHCb was done, a naive clone of the code from LHCb in Run2Support ends up in a number of clashes in library names, component names, headers names.

This MR fixes all the clashes, starting by renaming all libraries and removing pointlessly duplicated components, to then rename components that have to be duplicated (with a DD4hep and a DetDesc variants).

I also modernized a test that required some adaptation.

Note that this requires gaudi/Gaudi!1858 (merged) to actually work. Goes with Gauss!1240 too.