xdg-desktop-entries: reflect changes in makeDesktopItem API (#2496)

Based on nixpkgs commit c4b3aa62608d592d8a983be685f7e82000f4de30
stringBool is not needed because makeDesktopItem handles converting boolean parameters to string,
and noDisplay and prefersNonDefaultGPU parameters have been added.

tests/modules/misc/xdg/desktop-entries.nix

@@ -16,6 +16,8 @@ with lib;
         mimeType = [ "text/html" "text/xml" ];
         categories = [ "Network" "WebBrowser" ];
         startupNotify = false;
+        noDisplay = false;
+        prefersNonDefaultGPU = false;
         extraConfig = ''
           [X-ExtraSection]
           Exec=foo -o

tests/modules/misc/xdg/desktop-full-expected.desktop

@@ -8,6 +8,8 @@ Icon=test
 Keywords=calc;math
 MimeType=text/html;text/xml;
 Name=Test
+NoDisplay=false
+PrefersNonDefaultGPU=false
 StartupNotify=false
 Terminal=true
 Type=Application