Hook the default-app-setup OnLoad.cpp file with the cxxModuleProvider…

… from RNCLI (facebook#43049)

Summary:
Pull Request resolved: facebook#43049

This connects the OnLoad.cpp file used by OSS apps with the `rncli_cxxModuleProvider`.
This method is created by the CLI and takes care of querying all the TM CXX Modules discovered and returning them.

This PR is currently waiting on react-native-community/cli#2296

Changelog:
[Internal] [Changed] - Hook the default-app-setup OnLoad.cpp file with the cxxModuleProvider from RNCLI

Reviewed By: cipolleschi

Differential Revision: D53812109

packages/react-native/ReactAndroid/cmake-utils/default-app-setup/OnLoad.cpp

@@ -62,8 +62,16 @@ void registerComponents(
 std::shared_ptr<TurboModule> cxxModuleProvider(
     const std::string& name,
     const std::shared_ptr<CallInvoker>& jsInvoker) {
-  // Not implemented yet: provide pure-C++ NativeModules here.
-  return nullptr;
+  // Here you can provide your CXX Turbo Modules coming from
+  // either your application or from external libraries. The approach to follow
+  // is similar to the following (for a module called `NativeCxxModuleExample`):
+  //
+  // if (name == NativeCxxModuleExample::kModuleName) {
+  //   return std::make_shared<NativeCxxModuleExample>(jsInvoker);
+  // }
+
+  // And we fallback to the CXX module providers autolinked by RN CLI
+  return rncli_cxxModuleProvider(name, jsInvoker);
 }
 
 std::shared_ptr<TurboModule> javaModuleProvider(