Bug fixes for Dish (2nd round)

[Zeno-Zr]

• Remove redundant code left from shifting messages to DishManager.
• Print out the deleted dish instead of just "deleted dish".
• Update message used to print out when list of dishes is empty to match the rest of the features.
• Add regex checks to ensure numbers are not added as ingredients in both Parser and DishStorage. #146
• Update find dish to be case insensitive #131
• Update Add dish and DishStorage from adding dishes with duplicate names. #122 #141
• Add new method in DishManager to check if the pending dish has a description matching any dishes in the list of dishes.
• Updates messages to be printed to the console when the user tries to add a dish with a duplicate name, and/or the dish_list text file contains dishes with duplicate names.