Refactor ellipsis attributes and methods

Mostly changed to avoid repetition of code and remove the assumptions
about ellipsis being one code unit. The code for multi-code unit
ellipsis is not triggered yet, but is done in preparation for
potential future locale-dependent cases.

Test: bit CtsTextTestCases:*
Test: bit CtsWidgetTestCases:android.widget.cts.TextViewTest
Test: bit CtsWidgetTestCases:android.widget.cts.EditTextTest
Test: bit CtsWidgetTestCases:android.widget.cts.CheckedTextViewTest
Test: bit CtsWidgetTestCases:android.widget.cts.AutoCompleteTextViewTest
Test: bit CtsWidgetTestCases:android.widget.cts.MultiAutoCompleteTextViewTest
Test: adb shell am instrument -w -e package android.text com.android.frameworks.coretests/android.support.test.runner.AndroidJUnitRunner

Change-Id: Id1dfdc503f87fabed2447d55ab2107eee0eccd08