[TIMOB-18062] iOS: AttributedString Parity with Android

Jira: https://jira.appcelerator.org/browse/TIMOB-18062

iOS deprecation of Titanium.UI.IOS.AttributedString in favor of Titanium.UI.AttributedString. Pull request include Android support for AttributedString from pull request https://github.com/appcelerator/titanium_mobile/pull/6358, which will be closed once this PR is reviewed and merged.

Includes fix for font property in AttributedString, where fontsize was not working.
Add TiC.PROPERTY_ATTRIBUTE_RANGE to propertyAccessors. Those properties will be processed/changed in processProperties(KrollDict d) and propertyChanged(String key, Object oldValue, Object newValue, KrollProxy proxy). And you can get access to them using proxy.getProperty(String property) at any time.