[opentelemetry-kube-stack] Optionally install cert-manager CRDs

[rogercoll]

Cert-manager is the recommended dependency for managing Operator's webhooks TLS certificates: #1331

If cert-manager CRDs are not available on the k8s cluster, an additional Helm command will be need to deploy the kube-stack chart:

$ helm install cert-manager jetstack/cert-manager --namespace cert-manager --create-namespace --version v1.15.3 --set crds.enabled=true
$ helm install --create-namespace --namespace opentelemetry-operator-system opentelemetry-kube-stack open-telemetry/opentelemetry-kube-stack

It would be great if the kube-stack Chart could be installed as a single pipeline step, and conditionally add the cert-manager dependency. Has this been considered previously? Are there any known blockers?

Optional dependency

I have tried to add the cert-manager Helm Chart as an optional dependency to the kube-stack Chart and pospone the corresponding CRDs creation with annotations ("helm.sh/hook": post-install,post-upgrade), but I get timeout issue due this known issue cert-manager/cert-manager#1829

dependencies:
...
  - name: cert-manager
    version: v1.15.3
    repository: https://charts.jetstack.io
    alias: cert-manager
    condition: cert-manager.enabled

Another option would be to manually add cert-manager CRDs to the current crds internal kube-stack Chart: https://github.com/open-telemetry/opentelemetry-helm-charts/tree/main/charts/opentelemetry-kube-stack/charts/crds