Draft: Adding FluxCD for local setup

[lieberlois]

This PR drastically simplifies the local setup by adding FluxCD to deploy all infrastructure components. I moved to kind rather than k3d because I could not get flux working with the latter.

TODOS (before publishing the PR):

• Add deployment of application
• Figure out how to get flux to automatically detect manifests (no manual apply)
• Figure out difference between flux bootstrapand flux install
• Restructure local vs prod repo structure, e.g. like this to reduce duplication
• Change URI in observability-workshop/clusters/base/gitrepository.yaml
• Figure out a way to properly deploy ingress on kind
• Fix the breaking changes i just introduced