feat: bring new HDD related performance enhancements (#18239)

Optionally allows customers to enable 

- Enable an external cache to catch GET/HEAD responses 
- Enable skipping disks that are slow to respond in GET/HEAD 
  when we have already achieved a quorum

cmd/storage-rest-common.go

@@ -47,6 +47,7 @@ const (
 	storageRESTMethodStatInfoFile   = "/statfile"
 	storageRESTMethodReadMultiple   = "/readmultiple"
 	storageRESTMethodCleanAbandoned = "/cleanabandoned"
+	storageRESTMethodLinkXL         = "/linkxl"
 )
 
 const (