Make RuntimeExecutorSyncUIThreadUtils.h private

Summary:
Make `RuntimeExecutorSyncUIThreadUtils.h` private: switch it to `PrivateGuard.h` and drop it from the `<React/RuntimeExecutor.h>` umbrella.

Changelog: [Internal]

Differential Revision: D123376642

Author: j-piasecki

packages/react-native/ReactCommon/runtimeexecutor/React/RuntimeExecutor.h

@@ -31,7 +31,6 @@
 #define RN_UMBRELLA_CONTEXT 1
 
 #include <ReactCommon/RuntimeExecutor.h>
-#include <ReactCommon/RuntimeExecutorSyncUIThreadUtils.h>
 
 #undef RN_UMBRELLA_CONTEXT
 #pragma pop_macro("RN_UMBRELLA_CONTEXT")

packages/react-native/ReactCommon/runtimeexecutor/platform/cxx/ReactCommon/RuntimeExecutorSyncUIThreadUtils.h

@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <react/cxxstableapi/UmbrellaGuard.h>
+#include <react/cxxstableapi/PrivateGuard.h>
 
 #include <ReactCommon/RuntimeExecutor.h>
 

packages/react-native/ReactCommon/runtimeexecutor/platform/ios/ReactCommon/RuntimeExecutorSyncUIThreadUtils.h

@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <react/cxxstableapi/UmbrellaGuard.h>
+#include <react/cxxstableapi/PrivateGuard.h>
 
 #include <ReactCommon/RuntimeExecutor.h>