bisect-kit: Add support for multiple tast tests

1. eval_cros_tast.py will accept multiple tast tests seperated by comma.
2. Multiple performance tests will not be accepted.
3. The tests will be run one after another with "tast run" command to maintain the order.
4. The DUT will not be rebooted in between the tests. The DUT will only
   be rebooted once if the --reboot-before-test flag is passed.
5. The results.json file content will be appended.

BUG=b:313341761
TEST=./eval_cros_tast.py --chromeos-root /usr/local/google/home/cros-bisect-service/bisect-workdir/mul/chromeos --test-name " example.Pass , example.Pass  " chromeos8-row7-rack15-host22 --prebuilt --with-private-bundles --reboot-before-test
TEST=./run_tests.sh

Change-Id: I8372c035e5a4db19a660293f6a05628b6cc42485
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/bisect-kit/+/5569804
Commit-Queue: MD Nayeem Jahan Rafi <njrafi@chromium.org>
Tested-by: MD Nayeem Jahan Rafi <njrafi@chromium.org>
Reviewed-by: Cheng-Yu Lee <cylee@google.com>
2 files changed