Fixes playwright on linux, as reported in
https://github.com/denoland/deno/issues/16899#issuecomment-2378268454.
The issue was that we were opening the socket in nonblocking mode, which
meant that subprocesses trying to use it would get a `EWOULDBLOCK` error
(unexpectedly). The fix here is to only set nonblocking mode on our end
(which we need to use asynchronously)
Linux/macos only currently.
Part of https://github.com/denoland/deno/issues/23524 (fixes it on
platforms other than windows).
Part of #16899 (fixes it on platforms other than windows).
After this PR, playwright is functional on mac/linux.
