Core/Units: Partial implementation of SMSG_MOVE_SET_COLLISION_HGT - send proper character collision height on dismount.

Fixes #2642

NOTE: Still have to properly implement collision height calculation for mounting up.

src/server/game/Entities/Unit/Unit.cpp

@@ -11946,6 +11946,15 @@ void Unit::Unmount()
     SetUInt32Value(UNIT_FIELD_MOUNTDISPLAYID, 0);
     RemoveFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_MOUNT);
 
+    if (Player* thisPlayer = ToPlayer())
+    {
+        WorldPacket data(SMSG_MOVE_SET_COLLISION_HGT, GetPackGUID().size() + 4 + 4);
+        data.append(GetPackGUID());
+        data << uint32(sWorld->GetGameTime());   // Packet counter
+        data << thisPlayer->GetCollisionHeight();
+        thisPlayer->GetSession()->SendPacket(&data);
+    }
+
     WorldPacket data(SMSG_DISMOUNT, 8);
     data.appendPackGUID(GetGUID());
     SendMessageToSet(&data, true);