Update TextAssistant interface.

Rename to TextClassifier
Move to android.view.textclassifier package
Adds getTextClassifierInfo(...)
Changes addLinks(...) to getLinks(...)

This CL also integrates this interface with framework components
and passes a context to TextClassificationManager.

Test: Tests will be added with implementation.
Bug: 34661057
Change-Id: If9e90f034ebb702c1f78e72b6a844f39eebf738f