Move codegen output out of node_modules

Summary:
In this diff, it moves the codegen output location out of node_modules and to build/generated/ios folder.

A temp pod spec will be created so that those files will be included in the Xcode project.

Changelog: [Internal]

Reviewed By: hramos, cortinico

Differential Revision: D31809012

fbshipit-source-id: ba1c884c8024306ba0fd2102837b7dbebc6e18ac

Libraries/Settings/React-RCTSettings.podspec

@@ -36,11 +36,11 @@ Pod::Spec.new do |s|
   s.pod_target_xcconfig    = {
                                "USE_HEADERMAP" => "YES",
                                "CLANG_CXX_LANGUAGE_STANDARD" => "c++14",
-                               "HEADER_SEARCH_PATHS" => "\"$(PODS_ROOT)/RCT-Folly\""
+                               "HEADER_SEARCH_PATHS" => "\"$(PODS_ROOT)/RCT-Folly\" \"${PODS_ROOT}/Headers/Public/React-Codegen/react/renderer/components\""
                              }
 
   s.dependency "RCT-Folly", folly_version
-  s.dependency "FBReactNativeSpec", version
+  s.dependency "React-Codegen", version
   s.dependency "RCTTypeSafety", version
   s.dependency "ReactCommon/turbomodule/core", version
   s.dependency "React-jsi", version