Add log data capability in JUnit style tests

Similar to metric logging add data logging through our
testLog interface for test writers to report data.

Test: local run of cts with a modified test logging to
sponge.
https://sponge.corp.google.com/invocation?tab=TEST_SECURITY.txt&id=ad8237df-4e8a-47f4-9700-e05e8665f4c0&searchFor=
unit tests
Bug: 62219251

Change-Id: I970859749ce1eecd02b9008484bc1c9761e27136
6 files changed