Move tests with private APIs to coretests

Tests have been moved from CTS tests, with some small modifications.

Test: adb shell am instrument -w -e package android.text com.android.frameworks.coretests/android.support.test.runner.AndroidJUnitRunner
Bug: 37780152
Change-Id: I87ce084276db0f1157260bbeb0c9009c5227bfcf
9 files changed