test: move nix files

These are too much clutter. Move them to test directory until the test suite replacement is upstreamed.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/hsu/package.nix

@@ -1,23 +0,0 @@
-{
-  lib,
-  buildGoModule,
-  hakurei ? abort "hakurei package required",
-}:
-
-buildGoModule {
-  pname = "${hakurei.pname}-hsu";
-  inherit (hakurei) version;
-
-  src = ./.;
-  inherit (hakurei) vendorHash;
-  env.CGO_ENABLED = 0;
-
-  preBuild = ''
-    go mod init hsu >& /dev/null
-  '';
-
-  ldflags = lib.attrsets.foldlAttrs (
-    ldflags: name: value:
-    ldflags ++ [ "-X main.${name}=${value}" ]
-  ) [ "-s -w" ] { hakureiPath = "${hakurei}/libexec/hakurei"; };
-}