Lancer Core Bonus Enhancements

Adds mechanical support for the mount- and weapon-scoped core bonuses in the LANCER system: pin Auto-Stabilizing Hardpoints, Overpower Caliber or Superheavy Mounting to a weapon mount straight from the mech sheet. Auto-Stabilizing Hardpoints feeds its +1 Accuracy into attack rolls with that mount's weapons; Overpower Caliber offers its +1d6 bonus damage once per round, on a hit, when you roll damage.Implements the request in foundryvtt-lancer#724 as a standalone module. No system changes, no world migration.