Fix Make Unused Not Compiler Specific (#34357)

Summary:
Use of `__attribute__` and `__unused` is compiler specific. Opt for standard `[[maybe_unused]]` instead.

## Changelog

[General] [Fixed] - Remove compiler-specific syntax.

Pull Request resolved: https://github.com/facebook/react-native/pull/34357

Test Plan: Built on react-native-windows.

Reviewed By: cipolleschi

Differential Revision: D38498481

Pulled By: javache

fbshipit-source-id: af43206788f54dda3b747b6417e20096c7d520e8

ReactCommon/cxxreact/NativeToJsBridge.cpp

@@ -52,7 +52,7 @@ class JsToNativeBridge : public react::ExecutorDelegate {
   }
 
   void callNativeModules(
-      __attribute__((unused)) JSExecutor &executor,
+      [[maybe_unused]] JSExecutor &executor,
       folly::dynamic &&calls,
       bool isEndOfBatch) override {
     CHECK(m_registry || calls.empty())
@@ -85,7 +85,7 @@ class JsToNativeBridge : public react::ExecutorDelegate {
   }
 
   MethodCallResult callSerializableNativeHook(
-      __attribute__((unused)) JSExecutor &executor,
+      [[maybe_unused]] JSExecutor &executor,
       unsigned int moduleId,
       unsigned int methodId,
       folly::dynamic &&args) override {