Use Packet user states to report Ignition failures

[bgilbert]

Issue Report

Feature Request

Environment

Packet

Desired Feature

Packet allows reporting provisioning status to the console. Use this functionality to report Ignition failures, similar to coreos/bootengine#118. This will require adding e.g. curl to the initramfs.

For bonus points, we could also send a status update when Ignition starts/completes.

[crawford]

Ignition is learning how to do this with Azure. I think it makes sense to add it to the Packet OEM as well.