[Actors] [Items] Actor/Equipment Extensions

- Playing around with some actor/equipment syntax.
- Feeling out some potential extension methods for equipment.
[Actors] [Items] Actor/Equipment Extensions

- Implemented all of the changes to make it necessary to equip some enchanted items!
- The really cool part about the approach I've taken here is that I actually already know the mechanism for calculating stats for an actor based on the item enchantments doesn't actually work how I want it to in the future. Since I haven't coded the test to prove it, I won't worry about it right now. I'm confident the code can be extended to meet that requirement when I go over that bridge.
-- So, just what am I anticipating? Well, if I equip a one-time-use item (like a character drinking a potion, for example) then I want to ensure that the enchantment is applied once and then the item is destroyed.
- Moved one of my actor interfaces to the proper project since that was in a Core project instead.
- Renamed MutableStatCollection to StatCollection to follow my convention. I had the filename right before, but not the class.