tls: OpenDutPort and ExecDutCommand iteration

Iteration work on the APIs according to discussion.

Change-Id: I7e778758bb09accba8c2fbba17848a25f8e334ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2068464
Tested-by: Allen Li <ayatane@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Mike Nichols <mikenichols@chromium.org>
Commit-Queue: Allen Li <ayatane@chromium.org>
13 files changed