all: Use context in lib/dialer (#6177)

* all: Use context in lib/dialer

* a bit slimmer

* https://github.com/syncthing/syncthing/pull/5753

* bot

* missed adding debug.go

* errors.Cause

* simultaneous dialing

* anti-leak

lib/relay/client/dynamic.go

@@ -153,7 +153,7 @@ func relayAddressesOrder(ctx context.Context, input []string) []string {
 	buckets := make(map[int][]string)
 
 	for _, relay := range input {
-		latency, err := osutil.GetLatencyForURL(relay)
+		latency, err := osutil.GetLatencyForURL(ctx, relay)
 		if err != nil {
 			latency = time.Hour
 		}