[WIP] Loot System

Creating this PR for the loot system update. Currently all loot is tied to an entity (Loot class as an entity member) but blizz started using HighGuid::LootObject and all loot packets come with it. So it would make sense to split all loot into it's own container and lookup by loot guid. Also current loot system does not support currencies.

This commit enables basic looting functions and it could be merged as is but it may get complicated with this old system in the future. I hope to get some input on this.