Enhance the event store interface to support channeling (#7343)

- Avoids code duplication across the other targets. By having a
  centralized function call.

- Reduce the room for race.

pkg/event/targetlist.go

@@ -24,7 +24,8 @@ import (
 // Target - event target interface
 type Target interface {
 	ID() TargetID
-	Send(Event) error
+	Save(Event) error
+	Send(string) error
 	Close() error
 }
 
@@ -130,7 +131,7 @@ func (list *TargetList) Send(event Event, targetIDs ...TargetID) <-chan TargetID
 				wg.Add(1)
 				go func(id TargetID, target Target) {
 					defer wg.Done()
-					if err := target.Send(event); err != nil {
+					if err := target.Save(event); err != nil {
 						errCh <- TargetIDErr{
 							ID:  id,
 							Err: err,