Translate macros to python configuration files

[tomeichlersmith]

This task is pretty simple, but will take some time to make sure that they are working after translation.

Since we moved from using steering macros (in the Geant4 style), we have started using our own python configuration style to supply parameters to the simulation (through Simulator). The standardized macros we used in the past are still in the code base, and we should translate them to python configuration files (like the template ecalDigis or hcalDigis in the EventProc module) so that users can used the standardized simulation settings in the new version of ldmx-sw.

[tomeichlersmith]

Planned List of Python Configs to Write:

• [x] dark brem template (a few necessary inputs)
• [x] debugging geometry (no other inputs necessary)
• [x] simple, one electron beam template (input beam energy)
• Generators examples
  • [x] gun
  • [x] lhe
  • [x] multi
  • [ ] root
  • [x] gps
• UserAction examples
  • [x] Target Brem Filters
  • [x] Target Process Filters
  • [x] Track Process Filters
• Biasing Examples
  • [x] Dark Brem
  • [x] Photo-Nuclear
  • [x] Electron-Nuclear
  • [ ] Gamma->2Mu
• Production Examples
  • [x] 4GeV ECal PN
  • [x] 4GeV Target EN
  • [x] 4GeV Target PN