[MARKE-10] Basket Menu Implementation

[rayapetkova]

1. Make a button 'Basket' near the button 'Favourites' (top layout)
2. Make a new file 'basket.py' which contains only a function that returns the new scroll layout
3. Make functionality for the 'Basket' button - when it is clicked it needs to replace the category groupbox with the new scroll layout
4. If the user tries to add an item which is already in the basket, a pop-up message needs to be shown. We need to add two buttons for different options - 'Add more' and 'Cancel'
5. If the user tries to add an item with quantity greater than the available, a pop-up message needs to be shown saying "You have exceeded the available quantity of this product. Please choose a smaller quantity!"
6. The logic for the quantity needs to be implemented (for example when do we need to reduce the quantity of a product)

[rayapetkova]

Last changes: da2eed5

• Made a button 'Basket'
• Made a new file 'basket.py' in which we have a function basket_menu()
• When the 'Basket' button is clicked we hide the categories_groupbox and show the new scroll layout (the scroll_layout is returned from the basket_menu_function()
• When the user tries to add an item which already exists in the basket, a pop-up message is shown and says "Product already exists in basket."
• When the user tries to add an item with quantity greater than the available, a pop-up message is shown and says that he needs to choose a smaller one

Need to do:

• When the user wants to add an item which already exists in the basket we need to add two buttons 'Add more' and 'Cancel' to the error message
• The logic for the quantity
• How the user will remove items from the basket
• If the user can add an item from basket to favourites

[rayapetkova]

Last changes: 0b405f0

• The user can add a product from basket to favourites
• Added a remove button to every product in basket (its functionality is implemented and the query is executed successfully)
• Added a ToolTip to every button that refers to a product