(After GA)
This adds a unit test for the Unix domain sockets that I intend to use
for process splitting on Linux.
The length-prefixed encoding and decoding are copied from `subzone`, but
most of that code will not be re-used since it's Windows-specific and
also specific to a Chromium-like process model, which won't work for
Firezone.
Attempt at cleaning a couple things I missed in code review.
The old httpbin resource wasn't being used anyhow, so I just deduped
them and updated things in a couple other places that had drifted.
Hopefully this fixes the [flaky
CI](https://github.com/firezone/firezone/actions/runs/7918422653/job/21616835910)
This improves maintenance because we can now use a regular matrix for
the integration tests and one can locally use tools like shellcheck or a
`bash-lsp` during development.
---------
Signed-off-by: Jamil <jamilbk@users.noreply.github.com>
Co-authored-by: Jamil <jamilbk@users.noreply.github.com>
