Updates dynamic Kubelet config to use a structured status, rather than a
node condition. This makes the status machine-readable, and thus more
useful for config orchestration.
Fixes: #56896
This makes the Kubelet config key in the ConfigMap an explicit part of
the API, so we can stop using magic key names.
As part of this change, we are retiring ConfigMapRef for ConfigMap.
This PR unpacks the downloaded ConfigMap to a set of files on the node.
This enables other config files to ride alongside the
KubeletConfiguration, and the KubeletConfiguration to refer to these
cohabitants with relative paths.
This PR also stops storing dynamic config metadata (e.g. current,
last-known-good config records) in the same directory as config
checkpoints. Instead, it splits the storage into `meta` and
`checkpoints` dirs.
