Core/Auras: Implement SpellAuraInterruptFlags2::StartOfEncounter

Port From (https://github.com/TrinityCore/TrinityCore/commit/15135ce16f76d1635fa5606c99822b60bced94bf)

Source/Game/BattleGrounds/BattleGround.cs

@@ -407,6 +407,13 @@ namespace Game.BattleGrounds
                 SetStatus(BattlegroundStatus.InProgress);
                 SetStartDelayTime(StartDelayTimes[BattlegroundConst.EventIdFourth]);
 
+                foreach (var (guid, _) in GetPlayers())
+                {
+                    Player player = Global.ObjAccessor.FindPlayer(guid);
+                    if (player != null)
+                        player.AtStartOfEncounter();
+                }
+
                 // Remove preparation
                 if (IsArena())
                 {

Source/Game/Entities/Unit/Unit.cs

@@ -583,6 +583,14 @@ namespace Game.Entities
             return GetTransport();
         }
 
+        public void AtStartOfEncounter()
+        {
+            RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags2.StartOfEncounter);
+
+            if (IsAlive())
+                Unit.ProcSkillsAndAuras(this, null, new ProcFlagsInit(ProcFlags.EncounterStart), new ProcFlagsInit(), ProcFlagsSpellType.MaskAll, ProcFlagsSpellPhase.None, ProcFlagsHit.None, null, null, null);
+        }
+
         public void _RegisterDynObject(DynamicObject dynObj)
         {
             m_dynObj.Add(dynObj);

Source/Game/Maps/Instances/InstanceScript.cs

@@ -366,11 +366,7 @@ namespace Game.Maps
                             InitializeCombatResurrections(1, resInterval);
                             SendEncounterStart(1, 9, resInterval, resInterval);
 
-                            instance.DoOnPlayers(player =>
-                            {
-                                if (player.IsAlive())
-                                    Unit.ProcSkillsAndAuras(player, null, new ProcFlagsInit(ProcFlags.EncounterStart), new ProcFlagsInit(), ProcFlagsSpellType.MaskAll, ProcFlagsSpellPhase.None, ProcFlagsHit.None, null, null, null);
-                            });
+                            instance.DoOnPlayers(player => player.AtStartOfEncounter());
                             break;
                         }
                         case EncounterState.Fail: