network: NIC spoof matching tunnel (#912)

## Link to GitHub Issue or related Pull Request, if one exists
#911

## Description of change
Add tunnelhost/tunnelclient modes to -nicspoof so two cabs can do
LAN-style BPL matching over a real UDP path (including Wine), while
keeping the fake overlay NIC. Offline spoof remains available as before.

## Testing
DDR

src/spice2x/launcher/options.h

@@ -317,6 +317,9 @@ namespace launcher {
             DisableHighResTimer,
             EnableICMPHook,
             EnableNICSpoof,
+            NICSpoofIP,
+            NICSpoofHostRealIP,
+            NICSpoofPort,
             AutoElevate,
             CfgForceSoftwareRender,
             OBSWebSocketEnabled,