Export the forAll[,Local,Cross]Systems functions

flake.nix

@@ -66,7 +66,9 @@
           nixpkgs.lib // (import ./lib {
             inherit system localSystem crossSystem;
             pkgs = self.legacyPackages.${system};
-          }));
+          })) // {
+            inherit forAllSystems forAllLocalSystems forAllCrossSystems;
+          };
 
       legacyPackages =
         # The nixpkgs.legacyPackages after overlaying