Support using new powershell if available

[G-Rath]

It seems that tmux does not always prevent the console from being made weird 😬

There's a bit of a spider web of github issues, but the main takeaway is that while MS would love to fix it, it's very unlikely they'll be able to without breaking a lot of other things, and ideally just use the new powershell.

I've included a link to one of the issues that serve as an entry into the web for those wanting more details :)

You can reproduce the underlying issue by just running powershell.exe | true on WSL.

[kapoorlakshya]

@G-Rath Thanks again for your contribution!