Lootable Safehouse Keys

NPCs who give you keys to faction safehouses will now have them added to their inventories upon their deaths.
This is an espless implementation of ledzepiv's Lootable Safehouse Keys mod. When Julie Farkas, Colonel Hsu, Edgar Hardin, Nolan McNarma, or the guy at the Fort die, the corresponding faction safehouse key will be added to their inventories. This mod works using event handlers so there is no performance impact.