Improve handling of pwsh and cmd

[eugenesvk]

• disabled shell syntax check when it can't be or doesn't need to be done (closes PowerShell hasn't syntax checking option #3)
• add proper use of cmd with /c so that it doesn't persist (instead of -c)

Also, you might want to add pwsh, cmd to your project description

[anki-code]

Hi @eugenesvk ! Thanks for this! A few comments here.

[eugenesvk]

Updated, also cleaned the -c vs /C syntax a bit

[anki-code]

Looks good thanks @eugenesvk !