The prometheus metrics refractoring (#8003)

The measures are consolidated to the following metrics

- `disk_storage_used` : Disk space used by the disk.
- `disk_storage_available`: Available disk space left on the disk.
- `disk_storage_total`: Total disk space on the disk.
- `disks_offline`: Total number of offline disks in current MinIO instance.
- `disks_total`: Total number of disks in current MinIO instance.
- `s3_requests_total`: Total number of s3 requests in current MinIO instance.
- `s3_errors_total`: Total number of errors in s3 requests in current MinIO instance.
- `s3_requests_current`: Total number of active s3 requests in current MinIO instance.
- `internode_rx_bytes_total`: Total number of internode bytes received by current MinIO server instance.
- `internode_tx_bytes_total`: Total number of bytes sent to the other nodes by current MinIO server instance.
- `s3_rx_bytes_total`: Total number of s3 bytes received by current MinIO server instance.
- `s3_tx_bytes_total`: Total number of s3 bytes sent by current MinIO server instance.
- `minio_version_info`: Current MinIO version with commit-id.
- `s3_ttfb_seconds_bucket`: Histogram that holds the latency information of the requests.

And this PR also modifies the current StorageInfo queries

- Decouples StorageInfo from ServerInfo .
- StorageInfo is enhanced to give endpoint information.

NOTE: ADMIN API VERSION IS BUMPED UP IN THIS PR

Fixes #7873

cmd/fs-v1.go

@@ -252,10 +252,12 @@ func (fs *FSObjects) StorageInfo(ctx context.Context) StorageInfo {
 	if !fs.diskMount {
 		used = atomic.LoadUint64(&fs.totalUsed)
 	}
+	localPeer := GetLocalPeer(globalEndpoints)
 	storageInfo := StorageInfo{
-		Used:      used,
-		Total:     di.Total,
-		Available: di.Free,
+		Used:       []uint64{used},
+		Total:      []uint64{di.Total},
+		Available:  []uint64{di.Free},
+		MountPaths: []string{localPeer + fs.fsPath},
 	}
 	storageInfo.Backend.Type = BackendFS
 	return storageInfo