Party leave/disband done.

FFXIVClassic Map Server/packets/WorldPackets/Send/Group/PartyLeavePacket.cs

@@ -0,0 +1,30 @@
+using FFXIVClassic.Common;
+using FFXIVClassic_Map_Server.Actors;
+using FFXIVClassic_Map_Server.dataobjects;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+
+namespace FFXIVClassic_Map_Server.packets.WorldPackets.Send.Group
+{
+    class PartyLeavePacket
+    {
+        public const ushort OPCODE = 0x1021;
+        public const uint PACKET_SIZE = 0x28;
+
+        public static SubPacket BuildPacket(Session session, bool isDisband)
+        {
+            byte[] data = new byte[PACKET_SIZE - 0x20];
+            using (MemoryStream mem = new MemoryStream(data))
+            {
+                using (BinaryWriter binWriter = new BinaryWriter(mem))
+                {
+                    binWriter.Write((UInt16)(isDisband ? 1 : 0));
+                }
+            }
+            return new SubPacket(true, OPCODE, session.id, session.id, data);
+        }
+
+    }
+}