nixos/{containers,cri-o,podman}: move copyFile to nixos/lib/utils

nixos/lib/utils.nix

@@ -2,6 +2,11 @@ pkgs: with pkgs.lib;
 
 rec {
 
+  # Copy configuration files to avoid having the entire sources in the system closure
+  copyFile = filePath: pkgs.runCommandNoCC (builtins.unsafeDiscardStringContext (builtins.baseNameOf filePath)) {} ''
+    cp ${filePath} $out
+  '';
+
   # Check whenever fileSystem is needed for boot.  NOTE: Make sure
   # pathsNeededForBoot is closed under the parent relationship, i.e. if /a/b/c
   # is in the list, put /a and /a/b in as well.