Do not add LongLivedObject wrapper in OSS (facebook#35491)

Summary:
This change excludes the `LongLivedObject.h` file from the pod in the ReactCommon library.

The file creates a problem when the `use_frameworks!` option is used in an app because there can't be two files with the same name, despite being in different paths,
within the same framework. Specifically, this `LongLivedObject` is just a redirect to the other one, so it should be safe to exclude this.

## Changelog

[iOS][Fixed] - Exclude redirector to `LongLivedObject.h` from ReactCommon podspec

Pull Request resolved: facebook#35491

Test Plan: 1. Manually tested in an app from RC2

Differential Revision: https://internalfb.com/D41548985

Pulled By: cipolleschi

fbshipit-source-id: 5ff5b0eaf43fea4abd67f091482bd80fc11ec05c

ReactCommon/ReactCommon.podspec

@@ -62,6 +62,7 @@ Pod::Spec.new do |s|
       sss.source_files = "react/nativemodule/core/ReactCommon/**/*.{cpp,h}",
                          "react/nativemodule/core/platform/ios/**/*.{mm,cpp,h}"
       sss.dependency "React-jsidynamic", version
+      sss.exclude_files = "react/nativemodule/core/ReactCommon/LongLivedObject.h"
     end
 
     ss.subspec "samples" do |sss|