Enable SITL for MacOS

[mmosca]

Since the sitl binary for MacOS now works, we can enable Demo mode for MacOS as well. :)

Still missing Ser2TCP, but should be fixed by iNavFlight/inav#9365 and #1849

[Scavanger]

It's great that it also runs on Macs.

Shouldn't we also activate the SITL tab then?

/tabs/sitl.js: 81

 var os = GUI.operating_system;
    if (os != 'Windows' && os != 'Linux') {

        $('.content_wrapper').find('*').remove();
        $('.content_wrapper').append(`<h2>${i18n.getMessage('sitlOSNotSupported')}</h2>`);
        
        GUI.content_ready(callback);
        return;
    }