Cover react/renderer/viewtransition:viewtransition with Stable API guards (#57996)

Summary:
Pull Request resolved: #57996

Classifies `react/renderer/viewtransition:viewtransition` as a private target under the C++ stable API three-tier visibility model. Adds `#include <react/cxxstableapi/PrivateGuard.h>` to the module's only header, `ViewTransitionModule.h`, and declares the guard dependency in the build config (parent podspec is already configured).

Changelog: [Internal]

Reviewed By: zeyap

Differential Revision: D116452310

fbshipit-source-id: e7e6eec996d099b11797b3e9ed46ba074e93d6a1

Author: j-piasecki

packages/react-native/ReactCommon/react/renderer/viewtransition/CMakeLists.txt

@@ -15,6 +15,7 @@ target_include_directories(react_renderer_viewtransition PUBLIC ${REACT_COMMON_D
 
 target_link_libraries(react_renderer_viewtransition
         glog
+        react_cxxstableapi
         react_renderer_core
         react_renderer_mounting
         react_renderer_uimanager

packages/react-native/ReactCommon/react/renderer/viewtransition/ViewTransitionModule.h

@@ -7,6 +7,8 @@
 
 #pragma once
 
+#include <react/cxxstableapi/PrivateGuard.h>
+
 #include <queue>
 #include <unordered_set>