[PRINTING] Implement the undocumented MarshallDownStructure, MarshallDownStructuresArray, MarshallUpStructure, and MarshallUpStructuresArray to the extent I need and could find out through black-box testing.

PDBs reveal that these functions are also used in winspool.drv, but not imported from spoolss.dll to retain the client/server architecture.
As winspool.drv highly benefits from the MarshallUp* functions, I put them in a source file shared between spoolss.dll and winspool.drv.

The added API Tests cover my testing and all implemented features.
One more item done from https://reactos.org/wiki/Printing !

win32ss/printing/base/winspool/CMakeLists.txt

@@ -4,6 +4,7 @@ add_rpc_files(client ${REACTOS_SOURCE_DIR}/sdk/include/reactos/idl/winspool.idl)
 spec2def(winspool.drv winspool.spec ADD_IMPORTLIB)
 
 list(APPEND SOURCE
+    ../marshalling.c
     devmode.c
     forms.c
     jobs.c

win32ss/printing/base/winspool/precomp.h

@@ -15,8 +15,10 @@
 #include <winreg.h>
 #include <winspool.h>
 #include <winspool_c.h>
+#include <ndk/rtlfuncs.h>
 
 #include <spoolss.h>
+#include <marshalling/marshalling.h>
 
 #include <wine/debug.h>
 WINE_DEFAULT_DEBUG_CHANNEL(winspool);