Alerting: Support for simplified notification settings in rule API (#81011)

* Add notification settings to storage\domain and API models. Settings are a slice to workaround XORM mapping
* Support validation of notification settings when rules are updated

* Implement route generator for Alertmanager configuration. That fetches all notification settings.
* Update multi-tenant Alertmanager to run the generator before applying the configuration.

* Add notification settings labels to state calculation
* update the Multi-tenant Alertmanager to provide validation for notification settings

* update GET API so only admins can see auto-gen

pkg/tests/api/alerting/testing.go

@@ -226,13 +226,14 @@ func convertGettableGrafanaRuleToPostable(gettable *apimodels.GettableGrafanaRul
 		return nil
 	}
 	return &apimodels.PostableGrafanaRule{
-		Title:        gettable.Title,
-		Condition:    gettable.Condition,
-		Data:         gettable.Data,
-		UID:          gettable.UID,
-		NoDataState:  gettable.NoDataState,
-		ExecErrState: gettable.ExecErrState,
-		IsPaused:     &gettable.IsPaused,
+		Title:                gettable.Title,
+		Condition:            gettable.Condition,
+		Data:                 gettable.Data,
+		UID:                  gettable.UID,
+		NoDataState:          gettable.NoDataState,
+		ExecErrState:         gettable.ExecErrState,
+		IsPaused:             &gettable.IsPaused,
+		NotificationSettings: gettable.NotificationSettings,
 	}
 }
 
@@ -711,6 +712,13 @@ func (a apiClient) CreateMuteTimingWithStatus(t *testing.T, interval apimodels.M
 	return sendRequest[apimodels.MuteTimeInterval](t, req, http.StatusCreated)
 }
 
+func (a apiClient) EnsureMuteTiming(t *testing.T, interval apimodels.MuteTimeInterval) {
+	t.Helper()
+
+	_, status, body := a.CreateMuteTimingWithStatus(t, interval)
+	require.Equalf(t, http.StatusCreated, status, body)
+}
+
 func (a apiClient) UpdateMuteTimingWithStatus(t *testing.T, interval apimodels.MuteTimeInterval) (apimodels.MuteTimeInterval, int, string) {
 	t.Helper()
 
@@ -810,6 +818,43 @@ func (a apiClient) GetTimeIntervalByNameWithStatus(t *testing.T, name string) (a
 	return sendRequest[apimodels.GettableTimeIntervals](t, req, http.StatusOK)
 }
 
+func (a apiClient) CreateReceiverWithStatus(t *testing.T, receiver apimodels.EmbeddedContactPoint) (apimodels.EmbeddedContactPoint, int, string) {
+	t.Helper()
+
+	buf := bytes.Buffer{}
+	enc := json.NewEncoder(&buf)
+	err := enc.Encode(receiver)
+	require.NoError(t, err)
+
+	req, err := http.NewRequest(http.MethodPost, fmt.Sprintf("%s/api/v1/provisioning/contact-points", a.url), &buf)
+	req.Header.Add("Content-Type", "application/json")
+	require.NoError(t, err)
+
+	return sendRequest[apimodels.EmbeddedContactPoint](t, req, http.StatusAccepted)
+}
+
+func (a apiClient) EnsureReceiver(t *testing.T, receiver apimodels.EmbeddedContactPoint) {
+	t.Helper()
+
+	_, status, body := a.CreateReceiverWithStatus(t, receiver)
+	require.Equalf(t, http.StatusAccepted, status, body)
+}
+
+func (a apiClient) GetAlertmanagerConfigWithStatus(t *testing.T) (apimodels.GettableUserConfig, int, string) {
+	t.Helper()
+	req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("%s/api/alertmanager/grafana/config/api/v1/alerts", a.url), nil)
+	require.NoError(t, err)
+
+	return sendRequest[apimodels.GettableUserConfig](t, req, http.StatusOK)
+}
+
+func (a apiClient) GetActiveAlertsWithStatus(t *testing.T) (apimodels.AlertGroups, int, string) {
+	t.Helper()
+	req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("%s/api/alertmanager/grafana/api/v2/alerts/groups", a.url), nil)
+	require.NoError(t, err)
+	return sendRequest[apimodels.AlertGroups](t, req, http.StatusOK)
+}
+
 func sendRequest[T any](t *testing.T, req *http.Request, successStatusCode int) (T, int, string) {
 	client := &http.Client{}
 	resp, err := client.Do(req)