Fix using Swift in a native module with Fabric enabled (#33743)

Summary:
Using Fabric with a Swift native module is currently broken. There are currently two issues.

If you try to integrate a native module with Swift code, you will get the following error when running `pod install` with Fabric enabled:
```
[!] The following Swift pods cannot yet be integrated as static libraries:

The Swift pod `MyNativeView` depends upon `React-RCTFabric`, `React-Codegen`, `RCTTypeSafety`, and `ReactCommon`, which do not define modules.
To opt into those targets generating module maps (which is necessary to import them from Swift when building as static libraries),
you may set `use_modular_headers!` globally in your Podfile, or specify `:modular_headers => true` for particular dependencies.
```

To resolve this, I have applied the suggestion from the error (set `:modular_headers => true` for the appropriate modules inside `react_native_pods.rb`.

Afterwards, `pod install` succeeds but I still got `Redefinition of module 'React'` during the build due to the conflict inside the generated modulesmaps  `React-Core.modulemap` and `React-RCTFabric.modulemap`. This makes sense since `React-RCTFabric.podspec` has `s.header_dir = "React"` (see [here](https://github.com/facebook/react-native/blob/main/React/React-RCTFabric.podspec#L37)) and the module inherits that. However, we can explicitly specify `module_name` for the podspec which is what I have done. I have named the module `Fabric`, let me know if you think there's a better name.

## Changelog

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[iOS] [Fixed] - Fix using Swift in a native module with Fabric enabled

Pull Request resolved: #33743

Test Plan:
1. Clone [this](https://github.com/fortmarek/react-native) repo
2. From `main`, apply changes from [this](fortmarek@26958fc) commit (adding Swift file to the `MyNativeView` native module in the RN tester app)
3. Try to run `USE_FABRIC=1 RCT_NEW_ARCH_ENABLED=1 USE_CODEGEN_DISCOVERY=1 USE_HERMES=0 bundle exec pod install` inside the `packages/rn-tester`
4. Observe errors
5. Apply [the commit](9772c62) from this PR
6. Both pod install and the subsequent build should succeed.

I can also make changes to the current `MyNativeView` module to include Swift as well if it's something that the React Native Core team would be interested in - in case you want the Swift native modules to be always buildable on `main`

Reviewed By: dmitryrykun

Differential Revision: D36097852

Pulled By: cipolleschi

fbshipit-source-id: 2faebcffd1115339f89a406e265a6a040218dc9c

Author: fortmarek

React/React-RCTFabric.podspec

@@ -35,6 +35,7 @@ Pod::Spec.new do |s|
                              "**/android/*",
   s.compiler_flags         = folly_compiler_flags + ' ' + boost_compiler_flags
   s.header_dir             = "React"
+  s.module_name            = "RCTFabric"
   s.framework              = "JavaScriptCore"
   s.pod_target_xcconfig    = { "HEADER_SEARCH_PATHS" => "\"$(PODS_TARGET_SRCROOT)/ReactCommon\" \"$(PODS_ROOT)/boost\" \"$(PODS_ROOT)/DoubleConversion\" \"$(PODS_ROOT)/RCT-Folly\" \"$(PODS_ROOT)/Headers/Private/React-Core\" \"$(PODS_ROOT)/Headers/Public/React-Codegen\" \"${PODS_CONFIGURATION_BUILD_DIR}/React-Codegen/React_Codegen.framework/Headers\"" }
   s.xcconfig               = { "HEADER_SEARCH_PATHS" => "\"$(PODS_ROOT)/boost\" \"$(PODS_ROOT)/glog\" \"$(PODS_ROOT)/RCT-Folly\"", "CLANG_CXX_LANGUAGE_STANDARD" => "c++17",

scripts/react_native_pods.rb

@@ -44,7 +44,7 @@ def use_react_native! (options={})
   pod 'FBLazyVector', :path => "#{prefix}/Libraries/FBLazyVector"
   pod 'FBReactNativeSpec', :path => "#{prefix}/React/FBReactNativeSpec"
   pod 'RCTRequired', :path => "#{prefix}/Libraries/RCTRequired"
-  pod 'RCTTypeSafety', :path => "#{prefix}/Libraries/TypeSafety"
+  pod 'RCTTypeSafety', :path => "#{prefix}/Libraries/TypeSafety", :modular_headers => true
   pod 'React', :path => "#{prefix}/"
   pod 'React-Core', :path => "#{prefix}/"
   pod 'React-CoreModules', :path => "#{prefix}/React/CoreModules"
@@ -72,13 +72,13 @@ def use_react_native! (options={})
   pod 'React-runtimeexecutor', :path => "#{prefix}/ReactCommon/runtimeexecutor"
   pod 'React-perflogger', :path => "#{prefix}/ReactCommon/reactperflogger"
   pod 'React-logger', :path => "#{prefix}/ReactCommon/logger"
-  pod 'ReactCommon/turbomodule/core', :path => "#{prefix}/ReactCommon"
+  pod 'ReactCommon/turbomodule/core', :path => "#{prefix}/ReactCommon", :modular_headers => true
   pod 'Yoga', :path => "#{prefix}/ReactCommon/yoga", :modular_headers => true
 
   pod 'DoubleConversion', :podspec => "#{prefix}/third-party-podspecs/DoubleConversion.podspec"
   pod 'glog', :podspec => "#{prefix}/third-party-podspecs/glog.podspec"
   pod 'boost', :podspec => "#{prefix}/third-party-podspecs/boost.podspec"
-  pod 'RCT-Folly', :podspec => "#{prefix}/third-party-podspecs/RCT-Folly.podspec"
+  pod 'RCT-Folly', :podspec => "#{prefix}/third-party-podspecs/RCT-Folly.podspec", :modular_headers => true
 
   if ENV['USE_CODEGEN_DISCOVERY'] == '1'
     app_path = options[:app_path]
@@ -96,15 +96,15 @@ def use_react_native! (options={})
     generate_react_codegen_podspec!(react_codegen_spec)
   end
 
-  pod 'React-Codegen', :path => $CODEGEN_OUTPUT_DIR
+  pod 'React-Codegen', :path => $CODEGEN_OUTPUT_DIR, :modular_headers => true
 
   if fabric_enabled
     checkAndGenerateEmptyThirdPartyProvider!(prefix)
     pod 'React-Fabric', :path => "#{prefix}/ReactCommon"
     pod 'React-rncore', :path => "#{prefix}/ReactCommon"
     pod 'React-graphics', :path => "#{prefix}/ReactCommon/react/renderer/graphics"
     pod 'React-jsi/Fabric', :path => "#{prefix}/ReactCommon/jsi"
-    pod 'React-RCTFabric', :path => "#{prefix}/React"
+    pod 'React-RCTFabric', :path => "#{prefix}/React", :modular_headers => true
     pod 'RCT-Folly/Fabric', :podspec => "#{prefix}/third-party-podspecs/RCT-Folly.podspec"
   end