Add an alternate, simpler method for running signature test.

This change will allow the signature test to be executed just like a normal JUnit
based test, and will thus save a lot of unnecessary logic in the tradefed harness.

The existing signature test entry point is still retained, to avoid changing the
legacy CTS test harness.

Change-Id: I4a21811ee89c11960de99dfa4aa14df06a85afe4
4 files changed