Use core-tests-support instead of core-tests

The core-tests-support library is newly created. It doesn't have any
tests itself but some support for tests that need to use mocked classes
for testing. In this case, some tests are using TestKeyStore for SSL
testing in frameworks tests.

(cherry picked from commit c2d67283)

Bug: 10092469
Change-Id: Ib38364c607de5a98eb242050eaaf52b22ab8ca57