refactor: use controllers.DataPlane interface instead of concrete *dataplane.KongClient

[programmer04]

What this PR does / why we need it:

This PR decouples controllers from concrete *dataplane.KongClient in favor of using interface controllers.DataPlane..

Which issue this PR fixes:

closes #3794

Special notes for your reviewer:

The interface has to be extended to fit all use cases.

The only usage of concrete *dataplane.KongClient is left in

kubernetes-ingress-controller/internal/manager/run.go

Lines 326 to 367 in 70df8f6

	// setupKonnectNodeAgentWithMgr creates and adds Konnect NodeAgent as the manager's Runnable.
	// Returns error if failed to create Konnect NodeAgent.
	func setupKonnectNodeAgentWithMgr(
	c *Config,
	mgr manager.Manager,
	konnectNodeAPIClient *nodes.Client,
	dataplaneClient *dataplane.KongClient,
	clientsManager *clients.AdminAPIClientsManager,
	logger logr.Logger,
	instanceIDProvider *InstanceIDProvider,
	) error {
	var hostname string
	nn, err := util.GetPodNN()
	if err != nil {
	logger.Error(err, "Failed getting pod name and/or namespace, fallback to use hostname as node name in Konnect")
	hostname, _ = os.Hostname()
	} else {
	hostname = nn.String()
	logger.Info(fmt.Sprintf("Using %s as controller's node name in Konnect", hostname))
	}
	version := metadata.Release
	// Set channel to send config status.
	configStatusNotifier := clients.NewChannelConfigNotifier(logger)
	dataplaneClient.SetConfigStatusNotifier(configStatusNotifier)
	agent := konnect.NewNodeAgent(
	hostname,
	version,
	c.Konnect.RefreshNodePeriod,
	logger,
	konnectNodeAPIClient,
	configStatusNotifier,
	konnect.NewGatewayClientGetter(logger, clientsManager),
	clientsManager,
	instanceIDProvider,
	)
	if err := mgr.Add(agent); err != nil {
	return fmt.Errorf("failed adding konnect.NodeAgent runnable to the manager: %w", err)
	}
	return nil
	}

that is ok, otherwise, interface would have to be extended with the method

SetConfigStatusNotifier(clients.ConfigStatusNotifier)

that is only used in the above function. It would pollute the interface.

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.1 ⚠️

Comparison is base (e5969be) 65.3% compared to head (40aa94e) 65.3%.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #4383     +/-   ##
=======================================
- Coverage   65.3%   65.3%   -0.1%     
=======================================
  Files        154     154             
  Lines      17866   17866             
=======================================
- Hits       11678   11675      -3     
- Misses      5455    5456      +1     
- Partials     733     735      +2     

Impacted Files	Coverage Δ
...nal/controllers/configuration/object_references.go	87.3% <ø> (ø)
...nal/controllers/configuration/secret_controller.go	28.1% <ø> (ø)
...trollers/configuration/zz_generated_controllers.go	26.2% <ø> (ø)
...ternal/controllers/gateway/grpcroute_controller.go	16.0% <ø> (ø)
...l/controllers/gateway/referencegrant_controller.go	23.2% <ø> (ø)
...nternal/controllers/gateway/tcproute_controller.go	15.7% <ø> (ø)
...nternal/controllers/gateway/tlsroute_controller.go	16.1% <ø> (ø)
...nternal/controllers/gateway/udproute_controller.go	15.8% <ø> (ø)
internal/controllers/knative/knative.go	48.9% <ø> (ø)
internal/dataplane/kong_client.go	85.1% <ø> (-1.1%)	⬇️
... and 1 more

... and 3 files with indirect coverage changes

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