dns_exfil_random for windows

[william0901]

It will be good to add a similar script for windows

https://github.com/elastic/examples/blob/master/Machine%20Learning/Security%20analytics%20recipes/DNS_Data_Exfiltration/scripts/dns_exfil_random_osx.sh

[gingerwizard]

+1 contributions welcome. I'm not massively familiar with windows but will try if no one else has this to hand.