Fix Privacy Manifest generator when it does not contain a NSPrivacyAccessedAPITypes key (#44628)

Summary:
XCode privacy files might not contain a `NSPrivacyAccessedAPITypes` key, which causes the following error:

```
[!] An error occurred while processing the post-install hook of the Podfile.

undefined method `each' for nil

node_modules/react-native/scripts/cocoapods/privacy_manifest_utils.rb:111:in `block (4 levels) in get_used_required_reason_apis'
node_modules/react-native/scripts/cocoapods/privacy_manifest_utils.rb:106:in `each'
node_modules/react-native/scripts/cocoapods/privacy_manifest_utils.rb:106:in `block (3 levels) in get_used_required_reason_apis'
```

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[IOS] [FIXED] - Privacy Manifest aggregation failing due to no `NSPrivacyAccessedAPITypes` key

Pull Request resolved: #44628

Test Plan: I tested this patch on our own app and it solved the issue.

Reviewed By: christophpurrer

Differential Revision: D57618425

Pulled By: cipolleschi

fbshipit-source-id: 1a36ab5a1bb45b8507d3663b782c95258d97c8a4

Author: renchap

packages/react-native/scripts/cocoapods/privacy_manifest_utils.rb

@@ -105,7 +105,7 @@ def self.get_used_required_reason_apis(installer)
                 if File.basename(file_path) == 'PrivacyInfo.xcprivacy'
                     content = Xcodeproj::Plist.read_from_path(file_path)
                     accessed_api_types = content["NSPrivacyAccessedAPITypes"]
-                    accessed_api_types.each do |accessed_api|
+                    accessed_api_types&.each do |accessed_api|
                       api_type = accessed_api["NSPrivacyAccessedAPIType"]
                       reasons = accessed_api["NSPrivacyAccessedAPITypeReasons"]
                       next unless api_type