Add sort command

[liaujianjie]

Description

Adds a sort command that sorts the entries by their name in alphabetical order.

Example usage

|| ===================================================
|| Enter command: list
|| [Command entered:list]
|| 	1. Jane Doe  Phone Number: 234  Email: [email protected]
|| 	2. Bob Smith  Phone Number: 456  Email: [email protected]
|| 	3. John Doe  Phone Number: 123  Email: [email protected]
|| 	4. Alice Smith  Phone Number: 345  Email: [email protected]
|| 
|| 4 persons found!
|| ===================================================
|| Enter command: sort
|| [Command entered:sort]
|| Address book has been sorted!
|| ===================================================
|| Enter command: list
|| [Command entered:list]
|| 	1. Alice Smith  Phone Number: 345  Email: [email protected]
|| 	2. Bob Smith  Phone Number: 456  Email: [email protected]
|| 	3. Jane Doe  Phone Number: 234  Email: [email protected]
|| 	4. John Doe  Phone Number: 123  Email: [email protected]
|| 
|| 4 persons found!
|| ===================================================

Checklist

• Feature implementation
• Zero regressions
• Tests
• Add to help command
• User documentation