Enhance Code Review Process with Custom Prompts, Language Selection, and Automated Testing

Overview:

This PR introduces significant enhancements to the code review automation process, including support for custom prompts, language selection, and integration of automated testing using pytest and pylint.

Changes:

Custom Prompts:

• Added support for user-defined custom prompts.
• Example usage: custom_prompt: "Give a rating from 1 to 10 for this code:".

Language Selection:

• ntroduced the ability to specify the language for code review responses.
• Default language is set to English (en).

Automated Testing:

• Implemented unit tests using pytest for core functionalities.

Refactoring:

• Modularized the code for better maintainability.
• Improved error handling and logging.
• Ensured compliance with PEP8 standards.