Build test_suites package for Brillo

This change enables brillo build to create Autotest package test_suites, which
is required to run suite jobs in Autotest based on given build.

Each board can specify its own list of test suites in AUTOTEST_TEST_SUITES.
If there is no board specific setting of AUTOTEST_TEST_SUITES, all suite control
files in autotest repo will be included.

Bug: 26971750
Change-Id: I69d27005f79edb134d307bb21105d5f0d0af41ae
TEST: verified in local build
1 file changed