Add listBucketObjectsVersions implementation (#8093)

This API implementation simply behaves like listObjects()
but returns back single version for each object, this
implementation should be considered dummy it is only
meant for some applications which rely on this.

cmd/generic-handlers.go

@@ -481,7 +481,6 @@ var notimplementedBucketResourceNames = map[string]bool{
 	"requestPayment": true,
 	"tagging":        true,
 	"versioning":     true,
-	"versions":       true,
 	"website":        true,
 }