Summary:

Currently, to enable New Architecture, there is a need of running RCT_NEW_ARCH_ENABLED=1 pod install. This change introduces new param in config file: project.ios.newArchEnabledwhich forces to run app with a given architecture. This change is caused by enabling pods installation in run-ios and build-ios commands (#2077) - currently, if someone ran RCT_NEW_ARCH_ENABLED=1 pod install and then added a package with native code, the script would disable New Arch. This PR allows to:

1. Install pods in run/build commands with an Architecture the project is using based on a value from Pods.xcodeproj/project.pbxproj
2. Force using the given architecture on iOS based on the project.ios.newArchEnabled field. In case anyone change the architecture by using a RCT_NEW_ARCH_ENABLED flag and the param in config is set, it will install the pods accordingly to the Architecture set in the config

Test Plan:

1. Init new project with nightly
2. Use run-ios and check if project ran correctly
3. Use RCT_NEW_ARCH_ENABLED=1 pod install and run-ios and verify if fabric: true in Metro console
4. Create react-native.config.js with the following content:

module.exports = {
  project: {
    ios: {
      newArchEnabled: false,
    },
  },
};

5. Run run-ios and verify fabric: true is not visible in Metro logs
6. Change value to true and run run-ios again - verify fabric: true is visible in Metro logs
7. Add a dependency containing native code e.g. react-native-gesture-handler to the project
8. Run run-ios again, let the pods install and verify fabric: true is set in the Metro logs
9. Run pod install in ios folder and run run-ios again, verify that pods are installed again and fabric: true is visible in Metro logs

Checklist

• Documentation is up to date to reflect these changes.
• Follows commit message convention described in CONTRIBUTING.md