libbinder/libbinder_ndk stability tests in VTS

These test platform/APEX APIs in addition to the app APIs which are
tested by CtsNdkBinderTestCases, and should be included in VTS for
maximum coverage.

Bug: 161501127
Test: tests pass (already on TH)
Change-Id: I19c9628b138d8a02374b1cf908eab015765c97b2