KongConsumerGroup status changes should trigger depending KongConsumer reconciliation

[czeslavo]

Problem Statement

When the status of KongConsumerGroup that a given KongConsumer depends on changes (e.g. its Programmed condition changes to True), it should trigger KongConsumer's reconciliation despite the fact the KongConsumer's generation and Programmed condition's observedGeneration are equal.

Proposed Solution

Keep the last observed generations of the KongConsumerGroups the KongConsumer references in the KongConsumer's status. Compare those with the current generation of every KongConsumerGroup referenced by a KongConsumer in the shouldUpdate function and decide based on that (observed generation != current generation => should update).

Additional Information

The issue was worked around in #638 by returning an error from the KongConsumer reconciler when any of the referenced KongConsumerGroups is not Programmed yet. It should be changed once we fix this issue.

Acceptance Criteria

• KongConsumer reconciliation is triggered on every KongConsumerGroup change (update is not skipped)
• KongConsumer can become Programmed even if the KongConsumerGroup is not programmed yet

[pmalek]

The same issue affects KonnectGatewayControlPlane and their groups: when e.g. one of the CP group members gets deleted or get its Programmed status condition changed from False to True we should reconcile the group as well and reflect its state in its status.

[pmalek]

This also affects removing targets of KongPluginBinding, re #805