Skin preference support for Safari on iOS < 12.2

[Dringsim]

• MediaQueryList.addEventListener() requires Safari 14+, use MediaQueryList.addListener() instead;
• Chrome < 66 and Safari on iOS < 12.2 doesn't fire input events when checking radio buttons, use the click event as a fallback;
• Space-separated parameters and alpha parameter in hsl() require Chrome 65+, Safari on iOS 12.2+, use commas and hsla() instead;
• Object.fromEntries() requires Chrome 73+, Safari on iOS 12.2+. Fortunately there's a lightweight polyfill for it;
• "once" event listener option requires Chrome 55+, Safari 10+;
• Don't load skins.citizen.preferences on Chrome < 54, Safari < 10, where prepend() is unavailable.

Tested on Chrome 54, Safari on iOS 11.2.