Detect Rosetta2 and warn if x86_64 is used on arm64

Running `pod install` from inside Rosetta2 can lead to problems, try
to avoid doing that by hinting users from use_react_native!() function.

   $ arch -x86_64 pod install
   Building RNTester with Fabric enabled.
   Building RNTester with Fabric enabled.
   Building RNTester with Fabric enabled.
   Analyzing dependencies
   Downloading dependencies
   Generating Pods project
   Integrating client project
   Pod installation complete! There are 63 dependencies from the Podfile and 50 total pods installed.

   [!] Do not use "pod install" from inside Rosetta2 (x86_64 emulation on arm64).

   [!]  - Emulated x86_64 is slower than native arm64

   [!]  - May result in mixed architectures in rubygems (eg: ffi_c.bundle files may be x86_64 with an arm64 interpreter)

   [!] Run "env /usr/bin/arch -arm64 /bin/bash --login" then try again.

scripts/react_native_pods.rb

@@ -16,6 +16,13 @@ def use_react_native! (options={})
   # Include Hermes dependencies
   hermes_enabled = options[:hermes_enabled] ||= false
 
+  if `/usr/sbin/sysctl -n hw.optional.arm64 2>&1`.to_i == 1 && !RUBY_PLATFORM.start_with?('arm64')
+    Pod::UI.warn 'Do not use "pod install" from inside Rosetta2 (x86_64 emulation on arm64).'
+    Pod::UI.warn ' - Emulated x86_64 is slower than native arm64'
+    Pod::UI.warn ' - May result in mixed architectures in rubygems (eg: ffi_c.bundle files may be x86_64 with an arm64 interpreter)'
+    Pod::UI.warn 'Run "env /usr/bin/arch -arm64 /bin/bash --login" then try again.'
+  end
+
   # The Pods which should be included in all projects
   pod 'FBLazyVector', :path => "#{prefix}/Libraries/FBLazyVector"
   pod 'FBReactNativeSpec', :path => "#{prefix}/React/FBReactNativeSpec"