Apply custom dev support headers to iOS HTTP requests

Summary:
## Summary:

Apply custom HTTP headers from `RCTDevSupportHttpHeaders` to all HTTP requests
sent through `RCTHTTPRequestHandler`. This ensures that auth tokens and other
custom headers configured via the dev support header API are included in
network requests made by the networking module (e.g. `fetch()`).

## Changelog:

[IOS][CHANGED] - Apply custom dev support HTTP headers to RCTHTTPRequestHandler requests

## Test Plan:

Verified that the request is copied to a mutable request and headers are applied
via `RCTDevSupportHttpHeaders` before creating the data task.

## Facebook:
Applied from nest/mobile/apps/atod-sample/patches/react-native+0.83.1+006+atod-ios-http-handler.patch

Differential Revision: D95037920

Author: cipolleschi

packages/react-native/Libraries/Network/RCTHTTPRequestHandler.mm

@@ -9,6 +9,7 @@
 
 #import <mutex>
 
+#import <React/RCTDevSupportHttpHeaders.h>
 #import <React/RCTNetworking.h>
 #import <ReactCommon/RCTTurboModule.h>
 
@@ -99,7 +100,9 @@ - (NSURLSessionDataTask *)sendRequest:(NSURLRequest *)request withDelegate:(id<R
                                            valueOptions:NSPointerFunctionsStrongMemory
                                                capacity:0];
   }
-  NSURLSessionDataTask *task = [_session dataTaskWithRequest:request];
+  NSMutableURLRequest *mutableRequest = [request mutableCopy];
+  [[RCTDevSupportHttpHeaders sharedInstance] applyHeadersToRequest:mutableRequest];
+  NSURLSessionDataTask *task = [_session dataTaskWithRequest:mutableRequest];
   [_delegates setObject:delegate forKey:task];
   [task resume];
   return task;