feat(nix-compat/nix_http): init parse_nar[info]_str

This moves the URL component parsing code we had in nar-bridge to
nix-compat.

We change the function signature to return an Option, not a
Result<_, StatusCode>.

This allows returning more appropriate error codes, as we can
ok_or(…) at the callsite, which we now do: on an upload to an
invalid path, we now return "unauthorized", while on a GET/HEAD, we
return "not found".

This also adds support to parse compression suffixes. While not
supported in nar-bridge, other users of nix-compat might very well want
to parse these paths.

Also fix the error message when parsing NAR urls, it mentioned 32, not
52, which is a copypasta error from the narinfo URL parsing code.

Change-Id: Id1be9a8044814b54ce68b125c52dfe933c9c4f74
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12260
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

tvix/Cargo.lock

@@ -2361,6 +2361,7 @@ dependencies = [
  "thiserror",
  "tokio",
  "tokio-test",
+ "tracing",
  "zstd",
 ]