#70 Handle group process termination

[nitaysol]

This PR solves the issue in #70

[mtkennerly]

Thanks for this! Just had a few small comments :)

[nitaysol]

I updated the implementation to use Windows’ built-in Job Object with KILL_ON_JOB_CLOSE, so child processes are terminated automatically without needing to iterate over all running processes.
I added tests to confirm the behavior, but I still want to run a few local tests on my machine :)
If you see anything in the code that should be adjusted, I’m open to suggestions.

Also, just a heads-up: VirusTotal (specifically the SecureAge engine) is flagging the .exe as malicious. That engine tends to give a lot of false positives, but I’m seeing the same flag even on the master build with --release.
Interestingly, the downloadable release binary is not flagged, so it might be something introduced recently - or maybe you’re signing the release binaries?

Link: https://www.virustotal.com/gui/file/920186ed1000f46f6d14b43e51c123a13869e37239d2727460bfb0d077cd58d4?nocache=1

[mtkennerly]

This is great 🎉 Thanks for the feature. I'll make a new release within the next day or two to get this out.

[mtkennerly]

Interestingly, the downloadable release binary is not flagged, so it might be something introduced recently - or maybe you’re signing the release binaries?

Nah, I don't do any signing. Maybe this is one of those situations where it builds trust after enough people have used a particular version? When I scanned the updated build here, it complained about Trojan:Script/Wacatac.B!ml, which I've definitely seen in some false positives before. It's only one complaint out of all the scans they run, so oh well 🙃