Fixes RCTReconnectingWebSocket connecting in infinite loop when stopped before it connects (#26864)

Summary:
When `[RCTReconnectingWebSocket stop]` is called and `[RCTReconnectingWebSocket  reconnect]` is scheduled afterwards (i.e. connection didn't happen before `[RCTReconnectingWebSocket stop]` being invoked), it will keep reconnecting forever.

Also fixes retain loop in block within `[RCTReconnectingWebSocket  reconnect]`. When RCTReconnectingWebSocket is stopped and reference to it set to nil, block in reconnect will still keep self alive and reconnecting forever.

I found this edge case when I tried to stop RCTPackagerConnection after some time, so it doesn't spam with `[] nw_socket_handle_socket_event [C34585.1:1] Socket SO_ERROR [61: Connection refused]` when we don' have Metro running (we have brownfield app, so iOS devs don't need Metro running most of the time).

## Changelog
[iOS] [Fixed] -  RCTReconnectingWebSocket is reconnecting infinitely when stopped before getting connected
Pull Request resolved: #26864

Test Plan:
- Put breakpoint into `[RCTReconnectingWebSocket  reconnect]`
- Start sample RN app **without having Metro running**
- Into AppDelegate add something like
```objc
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
   [RCTPackagerConnection.sharedPackagerConnection stop]
});
```
- After the previous block is dispatched reconnect should not be invoked anymore

Reviewed By: motiz88

Differential Revision: D19767742

Pulled By: rickhanlonii

fbshipit-source-id: dabb2369b06217b961e9d2611257c106d350f70c

Author: Lukas Weber

Libraries/WebSocket/RCTReconnectingWebSocket.m

@@ -20,6 +20,7 @@ @interface RCTReconnectingWebSocket () <RCTSRWebSocketDelegate>
 @implementation RCTReconnectingWebSocket {
   NSURL *_url;
   RCTSRWebSocket *_socket;
+  BOOL _stopped;
 }
 
 - (instancetype)initWithURL:(NSURL *)url queue:(dispatch_queue_t)queue
@@ -44,6 +45,7 @@ - (void)send:(id)data
 - (void)start
 {
   [self stop];
+  _stopped = NO;
   _socket = [[RCTSRWebSocket alloc] initWithURL:_url];
   _socket.delegate = self;
   [_socket setDelegateDispatchQueue:_delegateDispatchQueue];
@@ -52,6 +54,7 @@ - (void)start
 
 - (void)stop
 {
+  _stopped = YES;
   _socket.delegate = nil;
   [_socket closeWithCode:1000 reason:@"Invalidated"];
   _socket = nil;
@@ -64,11 +67,17 @@ - (void)webSocket:(RCTSRWebSocket *)webSocket didReceiveMessage:(id)message
 
 - (void)reconnect
 {
+  if (_stopped) {
+   return;
+  }
+
   __weak RCTSRWebSocket *socket = _socket;
+  __weak __typeof(self) weakSelf = self;
+
   dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
-    [self start];
+    [weakSelf start];
     if (!socket) {
-      [self reconnect];
+      [weakSelf reconnect];
     }
   });
 }