Alerting: Foundations of historian app. (#114463)

We have two historians in alerting - alert state and notification. The intention
of this app is to provide query capabilities for both.

In this initial commit, the existing /history API is simply cloned to the new
app. It is identical except that it will send Kubernetes-style error responses
instead of Grafana-style.

This approach was taken to implement the new app more iteratively - ideally we
would define a new API, but this requires quite a significant overhaul of the
backend code.

pkg/registry/apps/apps.go

@@ -11,6 +11,7 @@ import (
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/registry"
 	"github.com/grafana/grafana/pkg/registry/apps/advisor"
+	"github.com/grafana/grafana/pkg/registry/apps/alerting/historian"
 	"github.com/grafana/grafana/pkg/registry/apps/alerting/notifications"
 	"github.com/grafana/grafana/pkg/registry/apps/alerting/rules"
 	"github.com/grafana/grafana/pkg/registry/apps/annotation"
@@ -42,6 +43,7 @@ func ProvideAppInstallers(
 	annotationAppInstaller *annotation.AnnotationAppInstaller,
 	exampleAppInstaller *example.ExampleAppInstaller,
 	advisorAppInstaller *advisor.AdvisorAppInstaller,
+	alertingHistorianAppInstaller *historian.AlertingHistorianAppInstaller,
 ) []appsdkapiserver.AppInstaller {
 	installers := []appsdkapiserver.AppInstaller{
 		playlistAppInstaller,
@@ -75,6 +77,10 @@ func ProvideAppInstallers(
 	if features.IsEnabledGlobally(featuremgmt.FlagGrafanaAdvisor) {
 		installers = append(installers, advisorAppInstaller)
 	}
+	//nolint:staticcheck // not yet migrated to OpenFeature
+	if features.IsEnabledGlobally(featuremgmt.FlagKubernetesAlertingHistorian) && alertingHistorianAppInstaller != nil {
+		installers = append(installers, alertingHistorianAppInstaller)
+	}
 
 	return installers
 }