Decouple SSLSocketTest and SSLContextTest

These tests were depending on libcore.io classes that live in the main
libcore library and not the support library. In order to run these
against the RI we need to decouple the tests from libcore.io classes
that are not in the support library.

Test: cts-tradefed run cts -m CtsLibcoreTestCases -a arm64-v8a
Change-Id: I6b1186179021006ba43512a5a5d4fbb094143d8c