[TIMOB-18062] iOS and Android: AttributedString Parity

-Added Attribute Range to Property Accessors instead of creating set and get methods
-Docs able to compile
-Titanium.UI.iOS.Attribute and Titanium.UI.iOS.Attribute doc missing deprecated since 3.6.0
-Added attributePRoxyFor method to make code easier to understand
-Using property accessors in Label Proxy for Attributed String