Scrolling feature

[akayiz]

Add a scrolling feature in the levels menu, which may be later implemented in the command line too

Expectations:

• I expect to have a scrolling bar, placed at the right of the level menu, for it to change color when I hover on it, and when I press on it I can drag it and scroll downward or upward in the levels menu (You can contact @Abdallah-Moe-dev for assistance in the dragging part since he implemented it in the options menu)
• I expect to be able to have extra buttons/levels/categories in the levels menu, that I won't see unless I start scrolling downwards, and then the buttons that i used to see will disappear, and then i have to scroll upwards to see them (Normal scrolling functionality)
• I expect it to work smoothly like any scrolling bar
• (Hint) Use the View: class in SFML, it is the perfect tool for this task and will help you tremendously

Looks example: