Add support for tagged messages on the Layout Inspector

Summary:
Related diff [Litho]: D23243009

This diff adds support for a protocol for layout messages where the type is recursively encoded as:

```
{
 kind: "type",
 data: ???
}
```

We check if the message adheres to the new encoding, otherwise we fall back to the old behavior. If it's the new encoding, the message is traversed recursively flattening the types to EditorValue using the type hints provided.

Reviewed By: Andrey-Mishanin

Differential Revision: D23319619

fbshipit-source-id: 79e8886f8f5a0aea4ec32938f1d5cd2fd645a297

iOS/Plugins/FlipperKitLayoutPlugin/FlipperKitLayoutPlugin/FlipperKitLayoutPlugin.mm

@@ -20,6 +20,9 @@
 #import "SKTapListener.h"
 #import "SKTapListenerImpl.h"
 
+NSObject* parseLayoutEditorMessage(NSObject* message);
+NSObject* flattenLayoutEditorMessage(NSObject* field);
+
 @implementation FlipperKitLayoutPlugin {
   NSMapTable<NSString*, id>* _trackedObjects;
   NSString* _lastHighlightedNode;
@@ -246,6 +249,8 @@
     return;
   }
 
+  value = parseLayoutEditorMessage(value);
+
   SKNodeDescriptor* descriptor =
       [_descriptorMapper descriptorForClass:[node class]];
 
@@ -270,6 +275,45 @@
   }
 }
 
+/**
+ Layout editor messages are tagged with the types they contain, allowing for
+ heterogeneous NSArray and NSDictionary supported by Android and iOS. The method
+ parseLayoutEditorMessage traverses the message and flattens the messages to
+ their original types.
+ */
+NSObject* parseLayoutEditorMessage(NSObject* message) {
+  if ([message isKindOfClass:[NSDictionary class]]) {
+    NSDictionary* wrapper = (NSDictionary*)message;
+    if (wrapper[@"kind"]) {
+      NSObject* newData = wrapper[@"data"];
+      return flattenLayoutEditorMessage(newData);
+    }
+  }
+  return message;
+}
+
+NSObject* flattenLayoutEditorMessage(NSObject* field) {
+  if ([field isKindOfClass:[NSDictionary class]]) {
+    NSDictionary* wrapper = (NSDictionary*)field;
+    NSMutableDictionary* dictionary =
+        [[NSMutableDictionary alloc] initWithCapacity:[wrapper count]];
+    for (NSString* key in wrapper) {
+      NSObject* value = wrapper[key];
+      dictionary[key] = parseLayoutEditorMessage(value);
+    }
+    return dictionary;
+  } else if ([field isKindOfClass:[NSArray class]]) {
+    NSArray* wrapper = (NSArray*)field;
+    NSMutableArray* array =
+        [[NSMutableArray alloc] initWithCapacity:[wrapper count]];
+    for (NSObject* value in wrapper) {
+      [array addObject:parseLayoutEditorMessage(value)];
+    }
+    return array;
+  }
+  return field;
+}
+
 - (void)onCallGetSearchResults:(NSString*)query
                  withResponder:(id<FlipperResponder>)responder {
   const auto alreadyAddedElements = [NSMutableSet<NSString*> new];