KGO: add a page explaining Konnect related finalizers

### Where is the problem?

https://docs.konghq.com/gateway-operator/latest/guides/konnect-entities/architecture/

### What happened?

"Managing Konnect entities" guides are comprehensive and explain a lot of type specific use cases.

One thing that's missing is explaining the possible `finalizers` that objects can get from the operator.

### What did you expect to happen?

Object finalizers on Konnect resources can be explained.

Additionally, we could also add a short section in https://docs.konghq.com/gateway-operator/latest/get-started/konnect/create-konnectextension/ explaining `KonnectExtension`'s finalizers.

### Code of Conduct and Community Expectations

- [x] I agree to follow this project's Code of Conduct
- [x] I agree to abide by the Community Expectations

Start with the Konnect entities architecture page and the KonnectExtension creation page linked in the issue, then review the existing “Managing Konnect entities” guides for their treatment of finalizers. Document the finalizers that Konnect resources can receive from the operator and add a short KonnectExtension section; done means both referenced pages explain the relevant finalizers.

Written by the indexing model from the issue text.