[#476] cmd/container: Add async handlers

Add `addContainerAsyncNotificationHandler`
func that passed handler to container's
worker pool similar to how it is done in
reputation handlers.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

cmd/neofs-node/container.go

@@ -138,6 +138,7 @@ func initContainerService(c *cfg) {
 	)
 }
 
+// addContainerNotificationHandler adds handler that will be executed synchronously
 func addContainerNotificationHandler(c *cfg, sTyp string, h event.Handler) {
 	typ := event.TypeFromString(sTyp)
 
@@ -148,6 +149,19 @@ func addContainerNotificationHandler(c *cfg, sTyp string, h event.Handler) {
 	c.cfgContainer.subscribers[typ] = append(c.cfgContainer.subscribers[typ], h)
 }
 
+// addContainerAsyncNotificationHandler adds handler that will be executed asynchronously via container workerPool
+func addContainerAsyncNotificationHandler(c *cfg, sTyp string, h event.Handler) {
+	addContainerNotificationHandler(
+		c,
+		sTyp,
+		event.WorkerPoolHandler(
+			c.cfgContainer.workerPool,
+			h,
+			c.log,
+		),
+	)
+}
+
 func setContainerNotificationParser(c *cfg, sTyp string, p event.Parser) {
 	typ := event.TypeFromString(sTyp)