Add dependencies to layouthelper and ios descriptor pods (#2140)

Summary:
This diff makes sure that pod lib lint succeeds and the CI is green for iOS.

It got broken when I landed my changes for the refactoring of FlipperKitLayoutPlugin. It wasn't picked up by flipper-oss-ios-job as it builds sample app and sample app had all the paths to the header search path which individually FlipperKitLayoutHelpers and FlipperKitIOSDescriptors were missing.

I will add the validation of pods as a job in sandcastle when one touches FlipperKit pods, this will avoid such cases in future.

## Changelog

Pull Request resolved: https://github.com/facebook/flipper/pull/2140

Test Plan:
Imported from GitHub, without a `Test Plan:` line.

iOS jobs are green on CI in GH.

Reviewed By: passy

Differential Revision: D27417743

Pulled By: priteshrnandgaonkar

fbshipit-source-id: 17aa4b04bf9954c4bd138261103751a245409568

iOS/Plugins/FlipperKitPluginUtils/FlipperKitLayoutHelpers/FlipperKitLayoutHelpers/SKNodeDescriptor.h

@@ -7,7 +7,7 @@
 
 #import <UIKit/UIKit.h>
 
-#import <FlipperKitLayoutHelpers/FlipperKitLayoutDescriptorMapperProtocol.h>
+#import "FlipperKitLayoutDescriptorMapperProtocol.h"
 #import "SKNamed.h"
 #import "SKTouch.h"
 

iOS/Plugins/FlipperKitPluginUtils/FlipperKitLayoutHelpers/FlipperKitLayoutHelpers/SKTouch.h

@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-#import <FlipperKitLayoutHelpers/FlipperKitLayoutDescriptorMapperProtocol.h>
 #import <UIKit/UIKit.h>
+#import "FlipperKitLayoutDescriptorMapperProtocol.h"
 
 typedef void (^SKTouchFinishDelegate)(id<NSObject> currentNode);
 typedef void (^SKProcessFinishDelegate)(NSDictionary* tree);