Add observedGeneration to Operator's status spec

Thoughts on adding the observedGeneration status field to the Kubernetes Operator?
 
I saw this issue https://issues.apache.org/jira/browse/FLINK-30858 which is useful but the traditional thing would be to just update the observedGeneration when the reconciliation is complete. There is [tooling](https://github.com/Shopify/krane/blob/main/README.md#specifying-passfail-conditions) out there that requires this spec in order to determine if the reconciliation passed for CRDs. Not only that, but it is the expected flow: https://alenkacz.medium.com/kubernetes-operator-best-practices-implementing-observedgeneration-250728868792
 
I think we keep the current implementation of the reconciliation spec for now but at the same time, we can update the `status.observedGeneration`?
 
Mailing List Discussion: https://lists.apache.org/thread/1dv33dyqqh18qncot1c6lxgn02do6xnw