Core/Auras: Implemented SPELL_AURA_SET_FFA_PVP

Port From (https://github.com/TrinityCore/TrinityCore/commit/c57b012ee4e75dfb4c3d29b6c5f2308ae559aec4)

Source/Game/Entities/Player/Player.Combat.cs

@@ -631,7 +631,7 @@ namespace Game.Entities
             // @todo should we always synchronize UNIT_FIELD_BYTES_2, 1 of controller and controlled?
             // no, we shouldn't, those are checked for affecting player by client
             if (!pvpInfo.IsInNoPvPArea && !IsGameMaster()
-                && (pvpInfo.IsInFFAPvPArea || Global.WorldMgr.IsFFAPvPRealm()))
+                && (pvpInfo.IsInFFAPvPArea || Global.WorldMgr.IsFFAPvPRealm() || HasAuraType(AuraType.SetFFAPvp)))
             {
                 if (!IsFFAPvP())
                 {

Source/Game/Spells/Auras/AuraEffect.cs

@@ -6065,6 +6065,19 @@ namespace Game.Spells
             }
         }
 
+        [AuraEffectHandler(AuraType.SetFFAPvp)]
+        void HandleSetFFAPvP(AuraApplication aurApp, AuraEffectHandleModes mode, bool apply)
+        {
+            if (!mode.HasAnyFlag(AuraEffectHandleModes.Real))
+                return;
+
+            Player target = aurApp.GetTarget().ToPlayer();
+            if (!target)
+                return;
+
+            target.UpdatePvPState(true);
+        }
+        
         [AuraEffectHandler(AuraType.ModOverrideZonePvpType)]
         void HandleModOverrideZonePVPType(AuraApplication aurApp, AuraEffectHandleModes mode, bool apply)
         {