Core/Maps: Implemented PolygonBoundary

Port From (https://github.com/TrinityCore/TrinityCore/commit/aed08b8a82cd4c14a6831ace7e9c4065ce29c5a4)

Source/Game/Maps/AreaBoundary.cs

@@ -2,6 +2,7 @@
 // Licensed under the GNU GENERAL PUBLIC LICENSE. See LICENSE file in the project root for full license information.
 
 using Game.Entities;
+using System.Collections.Generic;
 
 namespace Game.Maps
 {
@@ -218,6 +219,23 @@ namespace Game.Maps
         float _maxZ;
     }
 
+    class PolygonBoundary : AreaBoundary
+    {
+        Position _origin;
+        List<Position> _vertices;
+
+        public PolygonBoundary(Position origin, List<Position> vertices, bool isInverted = false) : base(isInverted)
+        {
+            _origin = origin;
+            _vertices = vertices;
+        }
+
+        public override bool IsWithinBoundaryArea(Position pos)
+        {
+            return pos.IsInPolygon2D(_origin, _vertices);
+        }
+    }
+
     class BoundaryUnionBoundary : AreaBoundary
     {
         public BoundaryUnionBoundary(AreaBoundary b1, AreaBoundary b2, bool isInverted = false) : base(isInverted)