Konnect entities: Secrets to Credentials reconciler

[pmalek]

Problem Statement

In order to give users a familiar user interface when interacting with consumers and credentials, when implementing Konnect entities support, KGO has to allow using Secrets as objects storing consumers' credentials data.

Proposed implementation

To implement the above KGO will introduce a new reconciler which will watch Secrets and create Credential objects (type according to konghq.com/credential label on the Secret).

This issue tracks the effort of such a reconciler

Acceptance criteria

• KGO has a reconciler which watches Secrets that are used as credentials by KongConsumers and creates, updates and deletes Credential objects accordingly

[pmalek]

We decided (https://kongstrong.slack.com/archives/C079GK3KB9R/p1726741563403179?thread_ts=1726735862.213059&cid=C079GK3KB9R) to not provide this for the initial implementation and instead possibly implement this in the future release to allow users to use credentials in the "old" way (through KongConsumer credentials field).

#623 can be used as the base of the implementation for this.