Make MeasuredText.sCached field final

Change-Id: Id3be64c48be1bcf55ac1a4b00b76a40861bf2f61
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.

Change-Id: I70dc31c9fcddf256b515e2c16f581648bc8cf880
Merge "Use core-tests-support instead of core-tests"
Merge "Make MeasuredText.sCached field final"