fix(powershell): don't use Invoke-Expression if ExpectingInput

[alexsch01]

dang, my apologies for getting this out after the npm release

this prevents a performance/security regression with piping strings into npm/npx

This should block nodejs/node#58347

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echo "Hello" | npm help a=1,b=2,c=3

will use the old logic and print out

No matches in help for: a=1 b=2 c=3

---

npm help a=1,b=2,c=3

will use the new logic and print out

No matches in help for: a=1,b=2,c=3

---

This is the best compromise between convenience and security

[alexsch01]

@wraithgar can you review when you have a chance?

[alexsch01]

Cleaned up the if and else statements to make things easier to understand