Drop RCT_EXPORT_METHOD from RCTI18nManager TurboModule

Summary:
Changelog: [Internal]

`RCTI18nManager` is a TurboModule: it conforms to `NativeI18nManagerSpec` 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 `NativeI18nManagerSpec` 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.

Differential Revision: D113579882

Author: christophpurrer

packages/react-native/React/CoreModules/RCTI18nManager.mm

@@ -26,17 +26,17 @@ + (BOOL)requiresMainQueueSetup
   return NO;
 }
 
-RCT_EXPORT_METHOD(allowRTL : (BOOL)value)
+- (void)allowRTL:(BOOL)value
 {
   [[RCTI18nUtil sharedInstance] allowRTL:value];
 }
 
-RCT_EXPORT_METHOD(forceRTL : (BOOL)value)
+- (void)forceRTL:(BOOL)value
 {
   [[RCTI18nUtil sharedInstance] forceRTL:value];
 }
 
-RCT_EXPORT_METHOD(swapLeftAndRightInRTL : (BOOL)value)
+- (void)swapLeftAndRightInRTL:(BOOL)value
 {
   [[RCTI18nUtil sharedInstance] swapLeftAndRightInRTL:value];
 }