New Logic for food screens

Rewrote most of the logic for homePage.dart, replaced SpecifiedFoodScreen.dart with specifiedCategoryScreen.dart that has only new code in it, split some code in different parts so it is more convenient to work with. Huge changes, everything but ChatScreen.dart (even though I made no changes to it) seems to work, but further testing is required. Also all the pictures need to be reviewed and replaced if needed.