feat(konnect): support Secrets in KonnectAPIAuthConfiguration

[pmalek]

What this PR does / why we need it:

Add support for tokens in Secrets in KonnectAPIAuthConfiguration reconciler.

This allows the following:

kind: KonnectAPIAuthConfiguration
apiVersion: konnect.konghq.com/v1alpha1
metadata:
  name: konnect-api-auth
  namespace: default
spec:
  type: secretRef
  secretRef:
    name: konnect-api-auth-secret
  serverURL: eu.api.konghq.com
---
kind: Secret
apiVersion: v1
metadata:
  name: konnect-api-auth-secret
  namespace: default
  labels:
    konghq.com/credential: konnect
stringData:
  token: kpat_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

The konghq.com/credential=konnect is required to efficiently watch for changes in Secrets.

Depends on #456 and Kong/kubernetes-configuration#16

Which issue this PR fixes

Part of #431

Special notes for your reviewer:

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect significant changes

[mlavacca]

Could you add a CHANGELOG entry?

[randmonkey]

Looks like some existing code still importing Konnect related types from configurationv1alpha1. They should be also updated after Kong/kubernetes-configuration is bumped.

[pmalek]

Needed to rebase on main and resolve conflicts. PTAL.