Desktop: Add nix package to flake (#3258)

* update cargo-gpu, remove legacy-target-specs to fix nix builds

* add nix package to flake

* update cargo hash

* fix merge

---------

Co-authored-by: firestar99 <firestar99@sydow.cloud>

.nix/cef.nix

@@ -0,0 +1,26 @@
+{ pkgs }:
+
+let
+  libcef = pkgs.libcef.overrideAttrs (_: _: {
+    postInstall = ''
+      strip $out/lib/*
+    '';
+  });
+  cefPath = pkgs.runCommand "cef-path" {} ''
+    mkdir -p $out
+
+    ln -s ${libcef}/include $out/include
+    find ${libcef}/lib -type f -name "*" -exec ln -s {} $out/ \;
+    find ${libcef}/libexec -type f -name "*" -exec ln -s {} $out/ \;
+    cp -r ${libcef}/share/cef/* $out/
+
+    echo '${builtins.toJSON {
+      type = "minimal";
+      name = builtins.baseNameOf libcef.src.url;
+      sha1 = "";
+    }}' > $out/archive.json
+  '';
+in
+{
+  CEF_PATH = cefPath;
+}