chromeos_config: Explicit specify priorities

As we want to manage cts pool with priorities, we
add the ability to specify priority with numbers directly
without defined priority mapping.

BUG=b:62821305
TEST=unittest

Change-Id: Iaf2619631c79383a45ebbb1ed76a79b9e6320ba3
Reviewed-on: https://chromium-review.googlesource.com/585234
Commit-Ready: Ilja H. Friedel <ihf@chromium.org>
Tested-by: Ilja H. Friedel <ihf@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
(cherry picked from commit a68c1d410069bb1f0c4b9b43866f5416e2e5b1b9)
Reviewed-on: https://chromium-review.googlesource.com/595249
Commit-Queue: Po-Hsien Wang <pwang@chromium.org>
Tested-by: Po-Hsien Wang <pwang@chromium.org>
Reviewed-by: Po-Hsien Wang <pwang@chromium.org>
3 files changed