feat: implement a Keptn metrics provider

Add a Keptn metrics provider for two resources:
* KeptnMetric: Verify the value of a single metric.
* Analysis (via AnalysisDefinition): Run a Keptn analysis over an
  interval validating SLOs.

Signed-off-by: Florian Bacher <florian.bacher@dynatrace.com>

pkg/controller/controller.go

@@ -21,6 +21,8 @@ import (
 	"sync"
 	"time"
 
+	"k8s.io/client-go/rest"
+
 	"github.com/google/go-cmp/cmp"
 	"go.uber.org/zap"
 	corev1 "k8s.io/api/core/v1"
@@ -49,6 +51,7 @@ const controllerAgentName = "flagger"
 
 // Controller is managing the canary objects and schedules canary deployments
 type Controller struct {
+	kubeConfig           *rest.Config
 	kubeClient           kubernetes.Interface
 	flaggerClient        clientset.Interface
 	flaggerInformers     Informers
@@ -91,6 +94,7 @@ func NewController(
 	eventWebhook string,
 	clusterName string,
 	noCrossNamespaceRefs bool,
+	kubeConfig *rest.Config,
 ) *Controller {
 	logger.Debug("Creating event broadcaster")
 	flaggerscheme.AddToScheme(scheme.Scheme)
@@ -105,6 +109,7 @@ func NewController(
 	recorder.SetInfo(version, meshProvider)
 
 	ctrl := &Controller{
+		kubeConfig:           kubeConfig,
 		kubeClient:           kubeClient,
 		flaggerClient:        flaggerClient,
 		flaggerInformers:     flaggerInformers,