[2pt] Implement methods for item class [group task]

[Jitender Kumar]

• Implement methods:
• can_be_archived?() in the Item class
• should return true if published_date is older than 10 years
• otherwise, it should return false
• move_to_archive() in the Item class
• should reuse can_be_archived?() method
• should change the archived property to true if the result of the can_be_archived?() method is true
• should do nothing if the result of the can_be_archived?() method is false