Core/Quests: Implemented QUEST_OBJECTIVE_FLAG_KILL_PLAYERS_SAME_FACTION

Port From (https://github.com/TrinityCore/TrinityCore/commit/2ffedf30a9f177ba848bb74c1b41375ac6d734a9)

Source/Game/Entities/Player/KillRewarder.cs

@@ -222,7 +222,7 @@ namespace Game.Entities
                 _RewardHonor(player);
                 // 4.1.1 Send player killcredit for quests with PlayerSlain
                 if (_victim.IsTypeId(TypeId.Player))
-                    player.KilledPlayerCredit();
+                    player.KilledPlayerCredit(_victim.GetGUID());
             }
             // Give XP only in PvE or in Battlegrounds.
             // Give reputation and kill credit only in PvE.

Source/Game/Entities/Player/Player.Quest.cs

@@ -2229,9 +2229,9 @@ namespace Game.Entities
             UpdateQuestObjectiveProgress(QuestObjectiveType.Monster, (int)entry, 1, guid);
         }
 
-        public void KilledPlayerCredit()
+        public void KilledPlayerCredit(ObjectGuid victimGuid)
         {
-            UpdateQuestObjectiveProgress(QuestObjectiveType.PlayerKills, 0, 1);
+            UpdateQuestObjectiveProgress(QuestObjectiveType.PlayerKills, 0, 1, victimGuid);
         }
 
         public void KillCreditGO(uint entry, ObjectGuid guid = default)