Refactor RCT_handleKeyCommand to avoid concurrency issues (#42708)

Summary:
Pull Request resolved: #42708

When pressing `r` on simulator in Bridgeless mode, we have a race condition between:
- RCTKeyCommands evaluating the blocks to be invoked
- ReactNative invalidating the DevMenu with the list of RCTKeyCommands (on which ReactNative is iterating).

The fix checks which commands need to be executed, stores them in an array and then iterates on the array, which is local to the function call, avoiding any concurrency issue.

## Changelog:
[iOS][Fixed] - Refactored RCT_handleKeyCommand to avoid concurrency issues

Reviewed By: motiz88

Differential Revision: D53186262

fbshipit-source-id: 60ae8974a9df7289395c8a9e9abe2e34e4c40309

packages/react-native/React/Base/RCTKeyCommands.m

@@ -173,13 +173,24 @@ - (void)handleKeyUIEventSwizzle:(UIEvent *)event
 
 - (void)RCT_handleKeyCommand:(NSString *)input flags:(UIKeyModifierFlags)modifierFlags
 {
+  // In Bridgeless mode we might incur in some concurrency issues
+  // where the React Native instance is invalidated while iterating on the
+  // list of available commands.
+  // That will cleanup the set while iterating, which is a not allowed mutation.
+  // To work around that, we store the commands that we need to execute in a separate
+  // array, local to this function call, so we don't incur in concurrency issues
+  NSMutableArray<RCTKeyCommand *> *commandsToExecute = [NSMutableArray new];
   for (RCTKeyCommand *command in [RCTKeyCommands sharedInstance].commands) {
     if ([command matchesInput:input flags:modifierFlags]) {
       if (command.block) {
-        command.block(nil);
+        [commandsToExecute addObject:command];
       }
     }
   }
+
+  for (RCTKeyCommand *command in commandsToExecute) {
+    command.block(nil);
+  }
 }
 
 + (instancetype)sharedInstance