Move LocalPodspecPatch to dedicated file (#34025)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/34025

This diff moves the monkeypatch LocalPodspecPatch to a dedicated ruby file.
It also adds test for that

## Changelog
[iOS][Changed] - Move LocalPodspecPatch to dedicated file

Reviewed By: cortinico

Differential Revision: D37069361

fbshipit-source-id: 28fddb197484f45aa20ccac516c874e79448e999

scripts/cocoapods/local_podspec_patch.rb

@@ -0,0 +1,51 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+# Monkeypatch of `Pod::Lockfile` to ensure automatic update of dependencies integrated with a local podspec when their version changed.
+# This is necessary because local podspec dependencies must be otherwise manually updated.
+module LocalPodspecPatch
+    # Returns local podspecs whose versions differ from the one in the `react-native` package.
+    def self.pods_to_update(react_native_path: "../node_modules/react-native")
+        @@local_podspecs = Dir.glob("#{react_native_path}/third-party-podspecs/*").map { |file| File.basename(file, ".podspec") }
+        @@local_podspecs = @@local_podspecs.select do |podspec_name|
+
+            # Read local podspec to determine the cached version
+            local_podspec_path = File.join(
+                Dir.pwd, "Pods/Local Podspecs/#{podspec_name}.podspec.json"
+            )
+
+            # Local podspec cannot be outdated if it does not exist, yet
+            next unless File.exist?(local_podspec_path)
+
+            local_podspec = File.read(local_podspec_path)
+            local_podspec_json = JSON.parse(local_podspec)
+            local_version = local_podspec_json["version"]
+
+            # Read the version from a podspec from the `react-native` package
+            podspec_path = "#{react_native_path}/third-party-podspecs/#{podspec_name}.podspec"
+            current_podspec = Pod::Specification.from_file(podspec_path)
+            current_version = current_podspec.version.to_s
+            current_version != local_version
+      end
+      @@local_podspecs
+    end
+
+    # Patched `detect_changes_with_podfile` method
+    def detect_changes_with_podfile(podfile)
+      Pod::UI.puts "Invoke detect_changes_with_podfile patched method".red
+      changes = super(podfile)
+      return patch_detect_changes_with_podfile(changes)
+    end
+
+    def patch_detect_changes_with_podfile(changes)
+        @@local_podspecs.each do |local_podspec|
+            next unless changes[:unchanged].include?(local_podspec)
+
+            changes[:unchanged].delete(local_podspec)
+            changes[:changed] << local_podspec
+        end
+        changes
+    end
+end