Reduce visibility of CoreModulesPackage (facebook#41087)

Summary:
Pull Request resolved: facebook#41087

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.

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

Reviewed By: christophpurrer

Differential Revision: D50338546

fbshipit-source-id: 3f0ce4dd22ddfa6743760ad378e7c6e45ab58127

Author: mdvacca

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;