refactor(network): replace manual size calculations with packed structs

nit: clean up unused variable

Author: bobtista

Core/GameEngine/CMakeLists.txt

@@ -545,6 +545,7 @@ set(GAMEENGINE_SRC
     Include/GameNetwork/NetCommandRef.h
     Include/GameNetwork/NetCommandWrapperList.h
     Include/GameNetwork/NetPacket.h
+    Include/GameNetwork/NetPacketStructs.h
     Include/GameNetwork/NetworkDefs.h
     Include/GameNetwork/NetworkInterface.h
     Include/GameNetwork/networkutil.h