Add additional info for replication metrics API (#17293)

to track the replication transfer rate across different nodes,
number of active workers in use and in-queue stats to get
an idea of the current workload.

This PR also adds replication metrics to the site replication
status API. For site replication, prometheus metrics are
no longer at the bucket level - but at the cluster level.

Add prometheus metric to track credential errors since uptime

cmd/data-usage-utils.go

@@ -38,6 +38,7 @@ type BucketTargetUsageInfo struct {
 	ReplicaSize             uint64 `json:"objectReplicaTotalSize"`
 	ReplicationPendingCount uint64 `json:"objectsPendingReplicationCount"`
 	ReplicationFailedCount  uint64 `json:"objectsFailedReplicationCount"`
+	ReplicatedCount         uint64 `json:"objectsReplicatedCount"`
 }
 
 // BucketUsageInfo - bucket usage info provides
@@ -64,6 +65,7 @@ type BucketUsageInfo struct {
 	VersionsCount           uint64                           `json:"versionsCount"`
 	DeleteMarkersCount      uint64                           `json:"deleteMarkersCount"`
 	ReplicaSize             uint64                           `json:"objectReplicaTotalSize"`
+	ReplicaCount            uint64                           `json:"objectReplicaCount"`
 	ReplicationInfo         map[string]BucketTargetUsageInfo `json:"objectsReplicationInfo"`
 }