fix: Speed up multi-object delete by taking bulk locks (#8974)

Change distributed locking to allow taking bulk locks
across objects, reduces usually 1000 calls to 1.

Also allows for situations where multiple clients sends
delete requests to objects with following names

```
{1,2,3,4,5}
```

```
{5,4,3,2,1}
```

will block and ensure that we do not fail the request
on each other.

cmd/fs-v1.go

@@ -188,9 +188,9 @@ func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
 }
 
 // NewNSLock - initialize a new namespace RWLocker instance.
-func (fs *FSObjects) NewNSLock(ctx context.Context, bucket string, object string) RWLocker {
+func (fs *FSObjects) NewNSLock(ctx context.Context, bucket string, objects ...string) RWLocker {
 	// lockers are explicitly 'nil' for FS mode since there are only local lockers
-	return fs.nsMutex.NewNSLock(ctx, nil, bucket, object)
+	return fs.nsMutex.NewNSLock(ctx, nil, bucket, objects...)
 }
 
 // Shutdown - should be called when process shuts down.
@@ -490,7 +490,6 @@ func (fs *FSObjects) CopyObject(ctx context.Context, srcBucket, srcObject, dstBu
 // GetObjectNInfo - returns object info and a reader for object
 // content.
 func (fs *FSObjects) GetObjectNInfo(ctx context.Context, bucket, object string, rs *HTTPRangeSpec, h http.Header, lockType LockType, opts ObjectOptions) (gr *GetObjectReader, err error) {
-
 	if err = checkGetObjArgs(ctx, bucket, object); err != nil {
 		return nil, err
 	}