Added NTSubDescriptor files and SKSubDescriptor interface

Summary: Added NTSubDescriptor file which implements the SKSubDescriptor interface to pass all NT specific data to the Layout Component Descriptor.

Reviewed By: jknoxville

Differential Revision: D12840392

fbshipit-source-id: bff295e13e8531456428424b7e073aefe7e1ced4

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutComponentKitSupport/SKSubDescriptor.h

@@ -0,0 +1,29 @@
+/*
+ *  Copyright (c) 2018-present, Facebook, Inc.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+#import <UIKit/UIKit.h>
+
+@class SKComponentLayoutWrapper;
+
+/**
+ A SKSubDescriptor is an object which knows how to expose an Object of type T
+ to the SKLayoutDescriptor. This class is for frameworks wanting to pass data along
+ through the Layout Descriptor.
+ */
+@interface SKSubDescriptor : NSObject
+
+/**
+ This is the SubDescriptor name.
+ */
+- (NSString *) getName;
+
+/**
+ This is the data the SubDescriptor wants to pass up to the SKLayoutDescriptor.
+ */
+- (NSDictionary<NSString *, NSObject *> *)getDataForNode:(SKComponentLayoutWrapper *)node;
+
+@end