fix: calling programs with spaces on Windows

[Kha]

This entire API has been carefully optimized for maximum pain output

[Kha]

Well, something broke, but it seems more likely to be a Unicode problem with Lake (I think we're still not setting the code page to UTF-8) or something on the way to it.

[Kha]

Well, now the test isn't broken even without escaping. It might be some weird edge case like "CreateProcess with A\B C.exe "an arg" works, but only if A\B does not exist by itself" 🤷 .

[Kha]

Hah, successfully failed the test. Now to add back the fix.

error: unspecified system_category error (error code: 193)

[leanprover-community-mathlib4-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 1f732bb3b7fa8e93ca01c1b257668aee14d72d2d --onto 39e0b41fe1ab4d16f15efb0dc9bd7607a8941713. (2024-07-26 17:37:33)