dut_tracking: Add swarming_instance

Add swarming_instance field as dut tracker shares many of the same calls
as RoboCrop, therefore it needs to identify the swarming instance in use
rather than assume chromeos-swarming.

This should be transparent but allows for more flexibility in the
swarming_cli module.

Bug: chromium:1093415
Change-Id: I3e722f1723f0c637c673c166ae2d767b1ecbc6df
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2239083
Reviewed-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
Commit-Queue: Mike Nichols <mikenichols@chromium.org>
Tested-by: Mike Nichols <mikenichols@chromium.org>
2 files changed