[TIMOB-18062] iOS: AttributedString Parity with Android

Jira: https://jira.appcelerator.org/browse/TIMOB-18062

This PR is a continuation of https://github.com/appcelerator/titanium_mobile/pull/6409/ which came from #6358.

It addresses the comments by @pingwang2011 for the Android portion of the code. The doc is still not completed yet as Titanium.UI.iOS.Attribute and Titanium.UI.iOS.AttributedString yml files are missing the "deprecated".

The propertyAccessors is now used in AttributedStringProxy.java, AttributeProxy.java and LabelProxy.java.
https://github.com/appcelerator/titanium_mobile/pull/6409#discussion-diff-21472766
Removed this method:
"@Kroll.method @Kroll.setProperty
public void setRange (int[] range)"

>From pingwang2011:
>Don't need this method if TiC.PROPERTY_ATTRIBUTE_RANGE is added to propertyAccessors.