Fix .torrent file upload on iPadOS

Mobile Safari on iOS does report `ios` platform, but iPadOS reports `mac`
instead. It is common sense to check for touch points when this happens
to differentiate Mac and iPad.

PR #19822.
Closes #19057.

---------

Co-authored-by: Vladimir Golovnev <glassez@yandex.ru>

src/webui/www/private/upload.html

@@ -167,7 +167,7 @@
                 window.parent.closeWindows();
         });
 
-        if (Browser.platform === 'ios') {
+        if ((Browser.platform === 'ios') || ((Browser.platform === 'mac') && (navigator.maxTouchPoints > 1))) {
             $('fileselect').accept = ".torrent";
         }
     </script>