Reduce visibility of CoreModulesPackage

Summary:
CoreModulesPackage is not being used outside of its package (neither in OSS or at Meta), I'm reducing its visibiity to package.

If you are using this class, please contact us and we will consider increasing visibiity again.

bypass-github-export-checks

changelog: [Android][Breaking] Reduce visibility of CoreModulesPackage class

Reviewed By: christophpurrer

Differential Revision: D50338546

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/CoreModulesPackage.java

@@ -57,7 +57,7 @@
       TimingModule.class,
       UIManagerModule.class,
     })
-public class CoreModulesPackage extends TurboReactPackage implements ReactPackageLogger {
+class CoreModulesPackage extends TurboReactPackage implements ReactPackageLogger {
 
   private final ReactInstanceManager mReactInstanceManager;
   private final DefaultHardwareBackBtnHandler mHardwareBackBtnHandler;