[Standardization] KaaS Cluster Management Gitops Controller

[cah-hbaum]

This issue was created to provide a discussion ground for possible future standards. It is derived from #181 and on of the points not assigned any issue yet.
This issue should discuss the introduction of a Gitops Controller for Cluster Management.

---

Definition of Done:

• Cluster stacks are available, which unblocks this issue
• Conclusions are reached about all discussion topics
• A new issue for the creation of a standard (proposal) is created and linked

[cah-hbaum]

Notes from prioritization meeting 06-10-23:

• push the cluster control yaml to a GIT
• an event/controller checks the files and updates the cluster
  -> should be delayed by 3+ months until the cluster stacks are available