Geant4InputHandling: prevent adding same particle more than once

Geant4InputHandling: collectPrimaries: use the mask to place the daughter vertices rather than size of the map

Now every place where interaction->vertices map is being used, the mask is used as the key to the map, instead of something else

`imp` was removed in Python 3.12.

This fixes runtime errors like:

    libc++abi: __cxa_guard_acquire detected recursive initialization

Allow for XML processing of files relative to xml tag location (See issue https://github.com/AIDASoft/DD4hep/issues/1180 for details)

Co-authored-by: Andre Sailer <andre.philippe.sailer@cern.ch>