Core/AI: Add DoCastSelf helper.

(I have no idea why I never bothered to do this before, really. It had crossed my mind a few times.)

(cherry picked from commit ab0abdbde5fb70a88aba4ec05291ec717444abe8)

This discussion is more effort than it takes to change it.
(cherry picked from commit b52a6b857097ff0e540fa0b560df2cc61546603d)

src/server/game/AI/CoreAI/UnitAI.h

@@ -241,6 +241,7 @@ class TC_GAME_API UnitAI
 
         void DoCast(uint32 spellId);
         void DoCast(Unit* victim, uint32 spellId, bool triggered = false);
+        void DoCastSelf(uint32 spellId, bool triggered = false) { DoCast(me, spellId, triggered); }
         void DoCastVictim(uint32 spellId, bool triggered = false);
         void DoCastAOE(uint32 spellId, bool triggered = false);