Core/AI: Some more refactoring prep for #19930. CreatureAI::EnterCombat is now called CreatureAI::JustEngagedWith. There's also two new methods on UnitAI, though they're never invoked right now.

src/server/scripts/Pet/pet_hunter.cpp

@@ -65,7 +65,7 @@ class npc_pet_hunter_snake_trap : public CreatureScript
                 _isViper = false;
             }
 
-            void EnterCombat(Unit* /*who*/) override { }
+            void JustEngagedWith(Unit* /*who*/) override { }
 
             void Reset() override
             {