DMVP-6378: to have nginx ingress load balancer external/internet-facing by default

[mrdntgrn]

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[what-the-diff]

PR Summary

• Enhanced Documentation
  Updated the README.md to provide additional instructions for setting up Karpenter, particularly for VPCs created externally and usage of spot instances.

• Improved Configuration Flexibility for Nginix Ingress Controller
  The nginx_ingress_controller_config input variable has been expanded to include a new key, configs. This allows for custom configurations and scalable adaptations based on specific project requirements.

• Updated Default Version for Nginx Ingress Controller
  The default chart_version for the Nginx Ingress Controller is now 4.12.0, upgraded from 4.11.3, so users can now benefit from the latest fixes, improvements and added features in the newer version.

• Dynamic Default Configuration Application in Helm Release Resource
  The Helm release resource has been amended to use merged default configurations dynamically. This is achieved through a new custom_default_configs_merged module, enhancing code efficiency and readability.

• Inclusion of Annotations and Metrics in Nginix Ingress Controller Configuration
  Added logic to define annotations and metrics within the Nginx Ingress Controller configuration to provide better monitoring and control.