Fix cookies not being sent after a redirected response (#22178)

Summary:
Fixes https://github.com/facebook/react-native/issues/19376

On iOS, the `HTTPShouldHandleCookies` boolean has no effect when custom cookies are set (see https://developer.apple.com/documentation/foundation/nsmutableurlrequest/1415485-httpshouldhandlecookies?preferredLanguage=occ). Setting custom cookies prevents the cookies of a redirect response from being re-used in the subsequent request.
This is why issue https://github.com/facebook/react-native/issues/19376 is opened.
The fix is to intercept the redirect request, and to manually set the cookies. This effectively makes the Android and iOS behaviours converge.

Changelog:
----------
  [iOS] [Fixed] - Fix cookies not being sent on iOS after redirect
Pull Request resolved: https://github.com/facebook/react-native/pull/22178

Differential Revision: D13191961

Pulled By: shergin

fbshipit-source-id: 4445a2499034a9846c6d7c37c1f1b72c9fd30129

Libraries/Network/RCTHTTPRequestHandler.mm

@@ -108,6 +108,21 @@ totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend
   [delegate URLRequest:task didSendDataWithProgress:totalBytesSent];
 }
 
+- (void)URLSession:(NSURLSession *)session
+              task:(NSURLSessionTask *)task
+willPerformHTTPRedirection:(NSHTTPURLResponse *)response
+        newRequest:(NSURLRequest *)request
+ completionHandler:(void (^)(NSURLRequest *))completionHandler
+{
+  // Reset the cookies on redirect.
+  // This is necessary because we're not letting iOS handle cookies by itself
+  NSMutableURLRequest *nextRequest = [request mutableCopy];
+
+  NSArray<NSHTTPCookie *> *cookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:request.URL];
+  nextRequest.allHTTPHeaderFields = [NSHTTPCookie requestHeaderFieldsWithCookies:cookies];
+  completionHandler(nextRequest);
+}
+
 - (void)URLSession:(NSURLSession *)session
           dataTask:(NSURLSessionDataTask *)task
 didReceiveResponse:(NSURLResponse *)response