Create Management page

[Drakeoon]

Todo:

• The management page should show a full-screen view of items in the application
• User should be able to set theme primary color as well as upload brand logo
• User should be able to select a dark theme
• On item click there should appear a modal which allows you to modify item's properties: price, title, description, image, out/in stock
• There should also be a switch to make product out of stock (active: true/false or something like that)