[client] Offer injected ICMPv6 echo replies to packet capture (#6321)

client/firewall/uspfilter/forwarder/icmp.go

@@ -362,6 +362,10 @@ func (f *Forwarder) injectICMPv6Reply(id stack.TransportEndpointID, icmpPayload
 		return 0
 	}
 
+	if pc := f.endpoint.capture.Load(); pc != nil {
+		(*pc).Offer(fullPacket, true)
+	}
+
 	return len(fullPacket)
 }