Add number of versions in server info API (#14812)

The goal is to show the number of versions in the server info API.

cmd/data-usage-utils.go

@@ -60,6 +60,7 @@ type BucketUsageInfo struct {
 
 	ObjectsCount         uint64                           `json:"objectsCount"`
 	ObjectSizesHistogram map[string]uint64                `json:"objectsSizesHistogram"`
+	VersionsCount        uint64                           `json:"versionsCount"`
 	ReplicaSize          uint64                           `json:"objectReplicaTotalSize"`
 	ReplicationInfo      map[string]BucketTargetUsageInfo `json:"objectsReplicationInfo"`
 }
@@ -73,6 +74,9 @@ type DataUsageInfo struct {
 	// Objects total count across all buckets
 	ObjectsTotalCount uint64 `json:"objectsCount"`
 
+	// Objects total count across all buckets
+	VersionsTotalCount uint64 `json:"versionsCount"`
+
 	// Objects total size across all buckets
 	ObjectsTotalSize uint64                           `json:"objectsTotalSize"`
 	ReplicationInfo  map[string]BucketTargetUsageInfo `json:"objectsReplicationInfo"`