fix(ios): apply “overrideUserInterfaceStyle” to main app window

[hansemannn]

Fixes #13328

Ti.UI.overrideUserInterfaceStyle = Ti.UI.USER_INTERFACE_STYLE_DARK;

const win = Ti.UI.createWindow({
	backgroundColor: 'blue',
	title: 'Main Window'
});
win.add(Ti.UI.createLabel({ top: 100, text: 'Window-Title should be white!' }));

const btn = Ti.UI.createButton({
	title: 'Open Sub-Window'
});

btn.addEventListener('click', () => {
	const window = Ti.UI.createWindow({ title: 'Sub-Window', backgroundColor: 'red' });
	window.add(Ti.UI.createLabel({ top: 100, text: 'Window-Title should be white!' }));
	const nav = Ti.UI.createNavigationWindow({ window });
	nav.open({ modal: true });
});

win.add(btn);

const nav = Ti.UI.createNavigationWindow({ window: win });
nav.open();

[hansemannn]

@mbender74 Can you maybe review this one?

[hansemannn]

Anyone else (maybe @caspahouzer) who can test this?

[caspahouzer]

LGTM

[mbender74]

sorry, late for the party.... I will submit soon another fix for control the background color (in the screen black) to be able to coloring it as wanted....