Support DD4HEP sensitive detectors

[sethrj]

As with #1505, DD4HEP has options that dig into the various attributes of hits/step/track.

From https://github.com/AIDASoft/DD4hep/blob/a39add61ba8821ecf6952d1152b34127597fdfb9/DDG4/plugins/Geant4SDActions.cpp#L654, the TrackerCombine class has a lot of requirements:

• Track ID is used to cache+accumulate consecutive hits
• Pre- and post-step volume are used to determine whether the track is leaving the detector
• Track status is used to find whether the hit needs to be flushed as wel