swarm/network: Keep span across roundtrip (#19140)

* swarm/newtork: WIP Span request span until delivery and put

* swarm/storage: Introduce new trace across single fetcher lifespan

* swarm/network: Put span ids for sendpriority in context value

* swarm: Add global span store in tracing

* swarm/tracing: Add context key constants

* swarm/tracing: Add comments

* swarm/storage: Remove redundant fix for filestore

* swarm/tracing: Elaborate constants comments

* swarm/network, swarm/storage, swarm:tracing: Minor cleanup

swarm/network/stream/messages.go

@@ -300,7 +300,7 @@ func (p *Peer) handleOfferedHashesMsg(ctx context.Context, req *OfferedHashesMsg
 			return
 		}
 		log.Trace("sending want batch", "peer", p.ID(), "stream", msg.Stream, "from", msg.From, "to", msg.To)
-		err := p.SendPriority(ctx, msg, c.priority, "")
+		err := p.SendPriority(ctx, msg, c.priority)
 		if err != nil {
 			log.Warn("SendPriority error", "err", err)
 		}