blender.gpuChecks: add unwrapped

An unwrapped check for `nix run`-ing on the host platform,
instead of `nix build`-ing in the sandbox

E.g.:

```
❯ nix run -f ./. --arg config '{ cudaSupport = true; cudaCapabilities = [ "8.6" ]; cudaEnableForwardCompat = false; allowUnfree = true; }' -L blender.gpuChecks.cudaAvailable.unwrapped
Blender 4.0.1
Read prefs: "/home/user/.config/blender/4.0/config/userpref.blend"
CUDA is available
Blender quit
❯ nix build -f ./. --arg config '{ cudaSupport = true; cudaCapabilities = [ "8.6" ]; cudaEnableForwardCompat = false; allowUnfree = true; }' -L blender.gpuChecks
blender> Blender 4.0.1
blender> could not get a list of mounted file-systems
blender> CUDA is available
blender> Blender quit
```

pkgs/applications/misc/blender/default.nix

@@ -374,15 +374,7 @@ stdenv.mkDerivation (finalAttrs: {
       '';
 
     };
-    gpuChecks.cudaAvailable = { blenderWithCuda, runCommand }: runCommand
-      "blender-cuda-available"
-      {
-        nativeBuildInputs = [ blenderWithCuda ];
-        requiredSystemFeatures = [ "cuda" ];
-      }
-      ''
-        blender --background -noaudio --python-exit-code 1 --python ${./test-cuda.py} && touch $out
-      '' { };
+    gpuChecks = callPackage ./gpu-checks.nix { };
   };
 
   meta = {

pkgs/applications/misc/blender/gpu-checks.nix

@@ -0,0 +1,29 @@
+{
+  bash,
+  blender,
+  callPackage,
+  lib,
+  runCommand,
+  writeScriptBin,
+}:
+
+let
+  blenderWithCuda = blender.override {cudaSupport = true;};
+  name = "${blenderWithCuda.name}-check-cuda";
+  unwrapped = writeScriptBin "${name}-unwrapped" ''
+    #!${lib.getExe bash}
+    ${lib.getExe blenderWithCuda} --background -noaudio --python-exit-code 1 --python ${./test-cuda.py}
+  '';
+in
+{
+  cudaAvailable =
+    runCommand name
+      {
+        nativeBuildInputs = [unwrapped];
+        requiredSystemFeatures = ["cuda"];
+        passthru = {
+          inherit unwrapped;
+        };
+      }
+      "${name}-unwrapped && touch $out";
+}