E2418. Reimplement due_date.rb

[Dhruv-Kolhatkar]

Team: E2418
Team Members: Atharva Patil, Deepika Choudhary, Dhruv Kolhatkar
Mentor: Kalyan Karnati

Changelist -

• Renamed methods and variables to accurately describe their responsibilities.
• Refactored each method to comply with DRY (Don't Repeat Yourself), SRP (Single Responsibility Principle), and other Ruby conventions.
• Overrode the comparator operator for the DueDate class and replace the deadline_sort class method.
• Utilized Rails built-in APIs for tasks such as validation, scoping, and database access.
• Conducted code smell checks using Code Climate