ListObjects Metadata Caching (#10648)

Design: https://gist.github.com/klauspost/025c09b48ed4a1293c917cecfabdf21c

Gist of improvements:

* Cross-server caching and listing will use the same data across servers and requests.
* Lists can be arbitrarily resumed at a constant speed.
* Metadata for all files scanned is stored for streaming retrieval.
* The existing bloom filters controlled by the crawler is used for validating caches.
* Concurrent requests for the same data (or parts of it) will not spawn additional walkers.
* Listing a subdirectory of an existing recursive cache will use the cache.
* All listing operations are fully streamable so the number of objects in a bucket no 
  longer dictates the amount of memory.
* Listings can be handled by any server within the cluster.
* Caches are cleaned up when out of date or superseded by a more recent one.

cmd/bucket-replication.go

@@ -235,7 +235,8 @@ func replicateObject(ctx context.Context, objInfo ObjectInfo, objectAPI ObjectLa
 	replicationStatus := replication.Complete
 
 	// Setup bandwidth throttling
-	totalNodesCount := len(GetRemotePeers(globalEndpoints)) + 1
+	peers, _ := globalEndpoints.peers()
+	totalNodesCount := len(peers)
 	b := target.BandwidthLimit / int64(totalNodesCount)
 	var headerSize int
 	for k, v := range putOpts.Header() {