extension_host: Replace backslashes with forward slashes for cwd on Windows (#38072)

Instead of passing CWD verbatim from the Windows host with backslashes
and all, we now rewrite it into a more POSIX-happy format featuring
forward slashes which means `std::path::Path` operations now work within
WASI with Windows-style paths.

Release Notes:

- N/A
85f7bb6277Jakub Konka committed on 9/12/2025, 5:22:24 PM· committed by GitHubparent7377a89
2 files changedLine totals unavailable