Add comprehensive Answers for OOP Design Patterns

[mahmoodhamdi]

This pull request adds a complete set of questions and answers related to Object-Oriented Programming (OOP) Design Patterns. The content aims to provide a deeper understanding of design patterns, their significance, and their implementation, especially in the context of Flutter applications.

Changes Made:

• Comprehensive Q&A covering various aspects of OOP Design Patterns, including:
  • Definitions and explanations of common design patterns (creational, structural, behavioral).
  • Practical applications and benefits of using design patterns in software development.
  • The relationship between design patterns and principles like SOLID and clean code.
  • Insights into the challenges of implementing design patterns in different contexts.

Benefits:

• Facilitates better understanding and application of design patterns among developers.
• Serves as a valuable resource for both new and experienced developers working with Flutter.

Please review and provide any feedback or suggestions for improvement.