cros-test: Change to use cros_test_cli proto

It is the first CL of multiple CLs to enhance cros-test to support
multi-DUTs.
This CL changes request and response API from execution_service proto to
cros_test_cli proto.

New unit test has been added.

The new code has been tested with unit test, Tast and Tauto.

BUG=b:199941891
TEST=./fast_build.sh -T; cros-test --input ...tauto.json ....; cros-test --input ...test.json ....;

Change-Id: Ie685c45d3d83f2c083a7acb5b9d013096c9ea0e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/3214683
Reviewed-by: Derek Beckett <dbeckett@chromium.org>
Reviewed-by: Jesse McGuire <jessemcguire@google.com>
Commit-Queue: Seewai Fu <seewaifu@google.com>
Tested-by: Seewai Fu <seewaifu@google.com>
11 files changed