Use netcfg.exe instead of NPFInstall.exe to install npcap driver

[dmiller-nmap]

I think we can remove the -i, -i2, -u, and -u2 options from NPFInstall.exe in favor of invoking netcfg.exe, which is present on Windows by default:

netcfg.exe -l "C:\path\to\npcap.inf" -c s -i INSECURE_NPCAP