Declare RCTBundleURLProviderAllowPackagerServerAccess unconditionally (#57517)

Summary:
Declares `RCTBundleURLProviderAllowPackagerServerAccess` unconditionally and keeps every read of the flag gated, so the function is a no-op instead of a compile error when packager support is compiled out, the same shape as `RCTDevLoadingViewSetEnabled`.

The function exists only for out-of-tree callers (the header comment describes test runs disabling packager access, and nothing in this repo calls it), but it is declared only under `#if RCT_DEV_MENU | RCT_PACKAGER_LOADING_FUNCTIONALITY`, so it vanishes in Release and an unguarded call fails with `call to undeclared function 'RCTBundleURLProviderAllowPackagerServerAccess'`. That broke every Release CI build in expo/expo when expo/expo#47638 called it directly, worked around at the call sites in expo/expo#47688. Builds with packager support keep identical behavior and preprocessor output.

## Changelog:

[IOS] [CHANGED] - Declare `RCTBundleURLProviderAllowPackagerServerAccess` unconditionally (no-op when packager support is compiled out)

Pull Request resolved: #57517

Test Plan:
- Without the macros (Release defaults), compiling a call against the current headers fails with the ISO C99 undeclared-function error, and compiles with this change.
- With `-DDEBUG=1`, compiles before and after. Every read of `kRCTAllowPackagerAccess` stays inside the guard, so dev behavior is unchanged.
- Both files pass `clang-format --dry-run --Werror`, and `packages/rn-tester` builds in Release with this change. The RNTester unit suite (162 tests, run together with #57518 so the suite compiles) passes with 0 failures.

Reviewed By: christophpurrer

Differential Revision: D113812551

Pulled By: fabriziocucci

fbshipit-source-id: e3c3cda822ceb33a63f9d6295e3402f76809c189

Author: ramonclaudio

packages/react-native/React/Base/RCTBundleURLProvider.h

@@ -14,15 +14,15 @@
 RCT_EXTERN NSString *_Nonnull const RCTBundleURLProviderUpdatedNotification;
 RCT_EXTERN const NSUInteger kRCTBundleURLProviderDefaultPort;
 
-#if RCT_DEV_MENU | RCT_PACKAGER_LOADING_FUNCTIONALITY
 /**
  * Allow/disallow accessing the packager server for various runtime scenario.
  * For instance, if a test run should never access the packager, disable it
  * by calling this function before initializing React Native (RCTBridge etc).
- * By default the access is enabled.
+ * By default the access is enabled. When packager support is compiled out
+ * (neither RCT_DEV_MENU nor RCT_PACKAGER_LOADING_FUNCTIONALITY is set),
+ * calling this function is a no-op.
  */
 RCT_EXTERN void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed);
-#endif
 
 NS_ASSUME_NONNULL_BEGIN
 

packages/react-native/React/Base/RCTBundleURLProvider.mm

@@ -19,13 +19,14 @@
 
 const NSUInteger kRCTBundleURLProviderDefaultPort = RCT_METRO_PORT;
 
-#if RCT_DEV_MENU | RCT_PACKAGER_LOADING_FUNCTIONALITY
+// Declared unconditionally so out-of-tree callers link in every configuration,
+// same shape as RCTDevLoadingViewSetEnabled. Reads stay gated below, so this is
+// a no-op when packager support is compiled out.
 static BOOL kRCTAllowPackagerAccess = YES;
 void RCTBundleURLProviderAllowPackagerServerAccess(BOOL allowed)
 {
   kRCTAllowPackagerAccess = allowed;
 }
-#endif
 static NSString *const kRCTPackagerSchemeKey = @"RCT_packager_scheme";
 static NSString *const kRCTJsLocationKey = @"RCT_jsLocation";
 static NSString *const kRCTEnableDevKey = @"RCT_enableDev";