Sort notification channels alphabetically (#37426)

Even without the ability to control the sort order or to filter, this notably improves usability for long lists of notification channels.

Partially fixes #20067.

pkg/services/sqlstore/alert_notification_test.go

@@ -325,6 +325,10 @@ func TestAlertNotificationSQLAccess(t *testing.T) {
 				err := GetAllAlertNotifications(query)
 				So(err, ShouldBeNil)
 				So(len(query.Result), ShouldEqual, 4)
+				So(query.Result[0].Name, ShouldEqual, cmd4.Name)
+				So(query.Result[1].Name, ShouldEqual, cmd1.Name)
+				So(query.Result[2].Name, ShouldEqual, cmd3.Name)
+				So(query.Result[3].Name, ShouldEqual, cmd2.Name)
 			})
 		})