Add support for build target & model in plan.proto

Allow targeting build target & model in DUT Constraint.

BUG=b:158501318
TEST=./generate.sh

Change-Id: I76c7270a591e70012bfcb4c3edb14f976c33064e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2318277
Reviewed-by: C Shapiro <shapiroc@chromium.org>
Commit-Queue: Jason Kusuma <jkusuma@google.com>
Tested-by: Jason Kusuma <jkusuma@google.com>
2 files changed