Support different sources of ignition

[SchwarzM]

Summary

The ignition is currently one big file which holds several distinct parts of config at least:

• OS Config
• Network Config
• Kubernetes Config

I would want to expose these parts towards the different teams that need to provide input in a clean API.

Basic example

As a gardener operator i only write the ignition which adds the node to the cluster.
As a network operator i only write the ignition which enables the node to interact with the fabric.
As a ceph operator i can write an ignition which configures OS kernel settings towards the ceph use case.
As a kvm operator i can write an ignition which configures OS kernel settings towards the hypervisor case.

Motivation

We do not need to manage a huge ignition which can hold even conflicting information from different sources.

[SchwarzM]

previous ccloud iteration on this topic: https://codi.eu-nl-1.cloud.sap/ignition-bootstrap-provider