Core/Vehicle: Change vehicle accessories' phase according to the player on the vehicle

Port From (https://github.com/TrinityCore/TrinityCore/commit/6d5086da1747816e1a4e8518e16ab1923de22e1a)

Source/Game/Entities/Unit/Unit.cs

@@ -521,6 +521,23 @@ namespace Game.Entities
         {
             return m_vehicle != null ? m_vehicle.GetBase() : null;
         }
+
+        Unit GetVehicleRoot()
+        {
+            Unit vehicleRoot = GetVehicleBase();
+
+            if (!vehicleRoot)
+                return null;
+
+            for (; ; )
+            {
+                if (!vehicleRoot.GetVehicleBase())
+                    return vehicleRoot;
+
+                vehicleRoot = vehicleRoot.GetVehicleBase();
+            }
+        }
+        
         public Creature GetVehicleCreatureBase()
         {
             Unit veh = GetVehicleBase();

Source/Game/Phasing/PhasingHandler.cs

@@ -37,7 +37,8 @@ namespace Game
             for (var i = 0; i < unit.m_Controlled.Count; ++i)
             {
                 Unit controlled = unit.m_Controlled[i];
-                if (controlled.GetTypeId() != TypeId.Player)
+                if (controlled.GetTypeId() != TypeId.Player
+                    && controlled.GetVehicle() == null)                   // Player inside nested vehicle should not phase the root vehicle and its accessories (only direct root vehicle control does)
                     func(controlled);
             }
 
@@ -50,6 +51,17 @@ namespace Game
                         func(summon);
                 }
             }
+
+            Vehicle vehicle = unit.GetVehicleKit();
+            if (vehicle != null)
+            {
+                foreach (var seat in vehicle.Seats)
+                {
+                    Unit passenger = Global.ObjAccessor.GetUnit(unit, seat.Value.Passenger.Guid);
+                    if (passenger != null)
+                        func(passenger);
+                }
+            }
         }
 
         public static void AddPhase(WorldObject obj, uint phaseId, bool updateVisibility)