online: Add chain enum to select full reconstruction steps.

Changes:

• Replaces the --steps option in cbmreco with --chain,-x
• --chain takes a single argument to select reconstructions steps and a trigger type
• Possible values are:
  • Unpack,
  • DigiTrigger (Unpack + DigiTriggering),
  • Hitfind (Unpack + Hitfinding),
  • HitTrigger (Hitfind + Hit triggering),
  • CA (Unpack + Hitfinding + Tracking),
  • V0 (Tracking + V0 trigger)
• In parameters/online added one config file per trigger type.

TODO:

• Merge parameter update: CbmSoft/cbmroot_parameter!185