Grant the power to gerrit_client cmd to submit a change. Once
we create a change and update it via CMDchangeedit, we can
submit it if the service account has permission.

BUG=1207955
TEST=e2e

Change-Id: Ia3102641ffe5bb72f8f63ad80bf15b5478cf5a2a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3039331Reviewed-by: Dirk Pranke <dpranke@google.com>
Reviewed-by: Michael Moss <mmoss@chromium.org>
Commit-Queue: Xinan Lin <linxinan@chromium.org>