Support MinIO to be deployed on more than 32 nodes (#8492)

This PR implements locking from a global entity into
a more localized set level entity, allowing for locks
to be held only on the resources which are writing
to a collection of disks rather than a global level.

In this process this PR also removes the top-level
limit of 32 nodes to an unlimited number of nodes. This
is a precursor change before bring in bucket expansion.

cmd/gateway-unsupported.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"context"
+	"errors"
 
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/lifecycle"
@@ -28,6 +29,12 @@ import (
 // GatewayUnsupported list of unsupported call stubs for gateway.
 type GatewayUnsupported struct{}
 
+// NewNSLock is a dummy stub for gateway.
+func (a GatewayUnsupported) NewNSLock(ctx context.Context, bucket string, object string) RWLocker {
+	logger.CriticalIf(ctx, errors.New("not implemented"))
+	return nil
+}
+
 // ListMultipartUploads lists all multipart uploads.
 func (a GatewayUnsupported) ListMultipartUploads(ctx context.Context, bucket string, prefix string, keyMarker string, uploadIDMarker string, delimiter string, maxUploads int) (lmi ListMultipartsInfo, err error) {
 	return lmi, NotImplemented{}