Alerting: create wrapper for Alertmanager to enable org level isolation (#37320)

Introduces org-level isolation for the Alertmanager and its components.

Silences, Alerts and Contact points are not separated by org and are not shared between them.

Co-authored with @davidmparrott and @papagian

pkg/api/http_server.go

@@ -56,7 +56,7 @@ import (
 	"github.com/grafana/grafana/pkg/util/errutil"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
-	macaron "gopkg.in/macaron.v1"
+	"gopkg.in/macaron.v1"
 )
 
 func init() {
@@ -104,7 +104,7 @@ type HTTPServer struct {
 	PluginDashboardService *plugindashboards.Service               `inject:""`
 	AlertEngine            *alerting.AlertEngine                   `inject:""`
 	LoadSchemaService      *schemaloader.SchemaLoaderService       `inject:""`
-	Alertmanager           *notifier.Alertmanager                  `inject:""`
+	MultiOrgAlertmanager   *notifier.MultiOrgAlertmanager          `inject:""`
 	LibraryPanelService    librarypanels.Service                   `inject:""`
 	LibraryElementService  libraryelements.Service                 `inject:""`
 	SocialService          social.Service                          `inject:""`