Add functionality to allow users to select and jump between exercises

[thatvideoshopguy]

I would like to propose a new feature for the repository that enables users to select specific exercises or jump between different exercises. This would provide more flexibility for learners who want to focus on particular topics or revisit exercises they found challenging.

Current behaviour:

At present, users must complete the exercises in a linear order, with no option to select or jump between exercises based on their preferences or needs.

Proposed feature:

• Implement a command or menu system that allows users to select a specific exercise to work on.
• Allow users to jump between exercises, regardless of whether they have completed the current one.
• Ensure that the progress bar and any completion statistics are updated accordingly when users switch exercises.
• Optionally, provide a mechanism to save the user's progress within each exercise, so they can resume where they left off when they return to a previously attempted exercise.

Benefits:

This feature will give users more control over their learning experience by enabling them to focus on areas where they need more practice or explore topics they find interesting. It will also allow users to easily revisit previous exercises for review or further practice.