[#398] Support retryer

Add two strategy for PutBucketSettings request retryer:
* exponential backoff (increasing up to `max_backoff` delays with jitter)
* constant backoff (always the same `max_backoff` delay between requests)

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

api/handler/api.go

@@ -47,6 +47,9 @@ type (
 		BypassContentEncodingInChunks() bool
 		MD5Enabled() bool
 		ACLEnabled() bool
+		RetryMaxAttempts() int
+		RetryMaxBackoff() time.Duration
+		RetryStrategy() RetryStrategy
 	}
 
 	FrostFSID interface {
@@ -63,6 +66,13 @@ type (
 	}
 )
 
+type RetryStrategy string
+
+const (
+	RetryStrategyExponential = "exponential"
+	RetryStrategyConstant    = "constant"
+)
+
 var _ api.Handler = (*handler)(nil)
 
 // New creates new api.Handler using given logger and client.