TIMOB-18062

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. This PR is not completed yet. Do not merge this yet.

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".

For this PR, AttributedStringProxy.java is not using TiC.PROPERTY_ATTRIBUTES in propertyAccessors but I have done the change to the code to make it more readable.

The propertyAccessors is now used in AttributeProxy.java and LabelProxy.java.