fix(ios): fix privacy-related Filesystem APIs

[hansemannn]

This fixes an issue from the RC where the privacy-guards for createdAt, modifiedAt and spaceAvailable would be compiled out. With this approach, the privacy error is fixed, as the APIs are only accessed when directly being called by the user.

const win = Ti.UI.createWindow({
    backgroundColor: '#fff'
});

const btn = Ti.UI.createButton({
    title: 'Trigger'
});

btn.addEventListener('click', () => {
    const file = Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory, 'test.txt');
    file.write('Test');

    console.warn('createdAt', file.createdAt());
    console.warn('modifiedAt', file.modifiedAt());
    console.warn('spaceAvailable', file.spaceAvailable());
    console.warn('uptime', Ti.Platform.uptime);
});

win.add(btn);
win.open();