Core/Player: Move TradeData to its own file

(cherry picked from commit 2d7d6f505c6e4e08b5fbbd0bc88b46753191c7aa)

Conflicts:
	src/server/game/Entities/Item/Item.cpp
	src/server/game/Entities/Player/Player.cpp
	src/server/game/Entities/Player/Player.h
	src/server/game/Handlers/TradeHandler.cpp
	src/server/game/Spells/Spell.cpp

src/server/game/Spells/Spell.cpp

@@ -53,6 +53,7 @@
 #include "SpellHistory.h"
 #include "Battlefield.h"
 #include "BattlefieldMgr.h"
+#include "TradeData.h"
 
 extern pEffect SpellEffects[TOTAL_SPELL_EFFECTS];