Alerting: Update integration schema to support versions (#109969)

* add VersionedNotifierPlugin and method that converts NotifierPlugin to it

* return new schema if query parameter version=2

* add version to k8s model of integration

* fix open api snapshot

* add version to IntegrationConfig

* use current version on conversion

* create versioned integrations for test

pkg/api/alerting.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"net/http"
+	"slices"
 
 	"github.com/grafana/grafana/pkg/api/response"
 	contextmodel "github.com/grafana/grafana/pkg/services/contexthandler/model"
@@ -9,7 +10,10 @@ import (
 )
 
 func (hs *HTTPServer) GetAlertNotifiers() func(*contextmodel.ReqContext) response.Response {
-	return func(_ *contextmodel.ReqContext) response.Response {
+	return func(r *contextmodel.ReqContext) response.Response {
+		if r.Query("version") == "2" {
+			return response.JSON(http.StatusOK, slices.Collect(channels_config.GetAvailableNotifiersV2()))
+		}
 		return response.JSON(http.StatusOK, channels_config.GetAvailableNotifiers())
 	}
 }