feat: add cli crate and fix various endpoints

[ion232]

• Refactors the project structure to be workspace based with separate cli and lib crates.
• Cli currently has challenge, external_engine, puzzles and users commands.
• Adds missing challenge endpoints and fixes existing ones.
• Adds missing puzzle endpoints and fixes existing ones.
• Adds missing users endpoints and fixes existing ones.
• Improves visibility of auth errors.
• Upgrades crates to rust 2024 edition.
• Adds and updates offline test cases.
• Bring models into better alignment with openapi spec.
• Closes get_public_user_data and get_user_performance_statistics return json errors #81.