Drop RCT_EXPORT_METHOD from RCTRedBox TurboModule (#57678)

Summary:
Pull Request resolved: #57678

Changelog: [Internal]

`RCTRedBox` is a TurboModule: it conforms to `NativeRedBoxSpec` and implements `getTurboModule:` returning the codegen'd `...SpecJSI`. For TurboModules, the JS->ObjC dispatch is driven by codegen (the generated spec supplies the `selector` and argument kinds, invoked at runtime via `NSMethodSignature` / `NSInvocation`), not by the `RCT_EXPORT_METHOD` macro's `__rct_export__` metadata.

The exported methods here are async-void with concrete parameter types (no generic `id` requiring `RCTConvert` coercion), so the macro is not functionally required. Convert them to plain ObjC method declarations; conformance to the codegen'd `NativeRedBoxSpec` protocol keeps compiler-enforced signature parity.

Signature-only refactor with no change to the JS-facing API. Sync methods, methods with `id` params, and `constantsToExport` are intentionally left untouched.

Reviewed By: cortinico

Differential Revision: D113579880

fbshipit-source-id: 6ced9af5367dbee000fcb25a3b70ef1fd6016dc6

Author: christophpurrer

packages/react-native/React/CoreModules/RCTRedBox.mm

@@ -222,12 +222,12 @@ - (void)loadExtraDataViewController
   });
 }
 
-RCT_EXPORT_METHOD(setExtraData : (NSDictionary *)extraData forIdentifier : (NSString *)identifier)
+- (void)setExtraData:(NSDictionary *)extraData forIdentifier:(NSString *)identifier
 {
   [_extraDataViewController addExtraData:extraData forIdentifier:identifier];
 }
 
-RCT_EXPORT_METHOD(dismiss)
+- (void)dismiss
 {
   dispatch_async(dispatch_get_main_queue(), ^{
     [self->_controller dismiss];