nixos, nix-darwin: fix user packages install

It is insufficient to install the packages in `home.packages`, it has
to be `home.path`, which includes configured extra package outputs or
profile commands.

nix-darwin/default.nix

@@ -68,7 +68,7 @@ in
 
     users.users = mkIf cfg.useUserPackages (
       mapAttrs (username: usercfg: {
-        packages = usercfg.home.packages;
+        packages = [ usercfg.home.path ];
       }) cfg.users
     );
 

nixos/default.nix

@@ -85,7 +85,7 @@ in {
       })));
 
     users.users = mkIf cfg.useUserPackages
-      (mapAttrs (username: usercfg: { packages = usercfg.home.packages; })
+      (mapAttrs (username: usercfg: { packages = [ usercfg.home.path ]; })
         cfg.users);
 
     systemd.services = mapAttrs' (_: usercfg: