We're aiming to use this for testing immediately and better
logging/tracing in future, but to make the changes manageable breaking
them into a smaller series that don't directly achieve much.
kops-controller can now serve the instance group & cluster config to
nodes, as part of the bootstrap process.
This enables nodes to boot without access to the state
store (i.e. without S3 / GCS / etc permissions)
Feature-flagged behind the KopsControllerStateStore feature-flag.