fix: avoid race condition crash in [RCTDataRequestHandler invalidate] (#2383)

## Summary:

Upstreaming a fix by @ntre that fixes a crash we saw internally related
to `[_queue cancelAllOperations]`.

>Calling [_queue cancelAllOperations] will release all references to any
active operations.
>If the blocks of those operations have a reference to itself, it will
result in dangling pointers, which could conceptually trigger a later
crash if there's a race between the operation completing and it being
pulled out of the queue.
>
>Add explicit strong reference while block is running.
>For good measure, fix same pattern also in RCTFileRequestHandler.
>
>Note: separately, that this code is passing the op itself as a
requestToken to [delegate URLRequest:] methods is suspect. That delegate
can retain said token.

## Test Plan:

Tested internally.

Author: Saadnajmi

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

@@ -40,6 +40,13 @@ - (NSOperation *)sendRequest:(NSURLRequest *)request withDelegate:(id<RCTURLRequ
 
   __weak __block NSBlockOperation *weakOp;
   __block NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
+    // [macOS
+    NSBlockOperation *strongOp = weakOp;  // Strong reference to avoid deallocation during execution
+    if (strongOp == nil || [strongOp isCancelled]) {
+      return;
+    }
+    // macOS]
+
     // Get mime type
     NSRange firstSemicolon = [request.URL.resourceSpecifier rangeOfString:@";"];
     NSString *mimeType =
@@ -51,15 +58,15 @@ - (NSOperation *)sendRequest:(NSURLRequest *)request withDelegate:(id<RCTURLRequ
                                            expectedContentLength:-1
                                                 textEncodingName:nil];
 
-    [delegate URLRequest:weakOp didReceiveResponse:response];
+    [delegate URLRequest:strongOp didReceiveResponse:response]; // [macOS]
 
     // Load data
     NSError *error;
     NSData *data = [NSData dataWithContentsOfURL:request.URL options:NSDataReadingMappedIfSafe error:&error];
     if (data) {
-      [delegate URLRequest:weakOp didReceiveData:data];
+      [delegate URLRequest:strongOp didReceiveData:data]; // [macOS]
     }
-    [delegate URLRequest:weakOp didCompleteWithError:error];
+    [delegate URLRequest:strongOp didCompleteWithError:error]; // [macOS]
   }];
 
   weakOp = op;

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

@@ -48,12 +48,19 @@ - (NSOperation *)sendRequest:(NSURLRequest *)request withDelegate:(id<RCTURLRequ
 
   __weak __block NSBlockOperation *weakOp;
   __block NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
+    // [macOS
+    NSBlockOperation *strongOp = weakOp;  // Strong reference to avoid deallocation during execution
+    if (strongOp == nil || [strongOp isCancelled]) {
+      return;
+    }
+    // macOS]
+
     // Get content length
     NSError *error = nil;
     NSFileManager *fileManager = [NSFileManager new];
     NSDictionary<NSString *, id> *fileAttributes = [fileManager attributesOfItemAtPath:request.URL.path error:&error];
     if (!fileAttributes) {
-      [delegate URLRequest:weakOp didCompleteWithError:error];
+      [delegate URLRequest:strongOp didCompleteWithError:error]; // [macOS]
       return;
     }
 
@@ -70,14 +77,14 @@ - (NSOperation *)sendRequest:(NSURLRequest *)request withDelegate:(id<RCTURLRequ
                                            expectedContentLength:[fileAttributes[NSFileSize] ?: @-1 integerValue]
                                                 textEncodingName:nil];
 
-    [delegate URLRequest:weakOp didReceiveResponse:response];
+    [delegate URLRequest:strongOp didReceiveResponse:response]; // [macOS]
 
     // Load data
     NSData *data = [NSData dataWithContentsOfURL:request.URL options:NSDataReadingMappedIfSafe error:&error];
     if (data) {
-      [delegate URLRequest:weakOp didReceiveData:data];
+      [delegate URLRequest:strongOp didReceiveData:data]; // [macOS]
     }
-    [delegate URLRequest:weakOp didCompleteWithError:error];
+    [delegate URLRequest:strongOp didCompleteWithError:error]; // [macOS]
   }];
 
   weakOp = op;