Fix os.q's sleep on Windows when stdin is redirected

[Jebiel]

TorQ's current Windows implementation of os.sleep uses timeout.exe:

sleep:{x:string x; system("sleep ",x;"timeout /t ",x," >nul")[NT]}

When standard input is redirected, timeout.exe can fail because it expects an interactive console.

This can prevent RDB/IDB startup retries from working as intended and surface misleading os file-load errors instead.

Using non-interactive PowerShell Start-Sleep avoids this dependency on stdin:

sleep:{x:string x; system("sleep ",x;"powershell.exe -NoProfile -NonInteractive -Command Start-Sleep -Seconds ",x)[NT]}

[Jebiel]

I've created a PR for this (#759)