Simplify the dependencies migration for new libraries (#34619)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/34619

When it comes to migrate existing libraries, users needs to update their .podspec files with a bunch [of changes](https://reactnative.dev/docs/0.69/new-architecture-library-ios#add-folly-and-other-dependencies).
This diff groups those changes in a single function, so that contributors can just invoke that function to prepare their dependencies.

## Changelog

[iOS][Changed] - Add function to simplify podspecs

Reviewed By: cortinico

Differential Revision: D39312203

fbshipit-source-id: ed631839e07d472a1fdcba33310f9b1d94fe2fd7

packages/rn-tester/NativeModuleExample/ScreenshotManager.podspec

@@ -7,9 +7,6 @@ require "json"
 
 package = JSON.parse(File.read(File.join(__dir__, "../package.json")))
 
-folly_compiler_flags = '-DFOLLY_NO_CONFIG -DFOLLY_MOBILE=1 -DFOLLY_USE_LIBCPP=1 -Wno-comma -Wno-shorten-64-to-32'
-folly_version = '2021.07.22.00'
-
 Pod::Spec.new do |s|
   s.name            = "ScreenshotManager"
   s.version         = package["version"]
@@ -18,15 +15,14 @@ Pod::Spec.new do |s|
   s.homepage        = "https://github.com/facebook/react-native.git"
   s.license         = "MIT"
   s.platforms       = { :ios => "12.4", :tvos => "12.4" }
-  s.compiler_flags  = folly_compiler_flags + ' -Wno-nullability-completeness'
+  s.compiler_flags  = '-Wno-nullability-completeness'
   s.author          = "Facebook, Inc. and its affiliates"
   s.source          = { :git => "https://github.com/facebook/react-native.git", :tag => "#{s.version}" }
 
   s.source_files    = "**/*.{h,m,mm,swift}"
   s.requires_arc    = true
 
-  s.dependency "React-Core"
-  s.dependency "RCT-Folly", folly_version
+  install_modules_dependencies(s)
 
   # s.dependency "..."