Add @TestApi annotation to a few @hide APIs that were used in CTS.

CtsViewTestCases tests were using @hide APIs. This change makes some
of these APIs @TestApi, so CtsViewTestCases can just link againts test_current.

Test: make -j
Bug: 37778825
Change-Id: I685ab5f0d1d5fcb5557ce4d93fe4f55cc695ed3d
5 files changed