Group items in shopping lists based on labels (#319)

* Add data classes to hold food label information

- Created `GetFoodLabelResponse` data class to represent food label details
- Updated `GetFoodResponse` to include `label` property of type `GetFoodLabelResponse`

* Add backend to sort items in shopping lists by label

* Add UI code to sort items in shopping lists by label

* Use label from ShoppingListItem instead of Food

* Use list for ShoppingListItems and labels storage

* Fix incorrect routing code

* Only add DefaultLabel if there are items with a label

* Small improvements to comments and formatting

ui/src/main/kotlin/gq/kirmanak/mealient/ui/components/LazyColumnWithLoadingState.kt

@@ -92,4 +92,3 @@ fun <T> LazyColumnWithLoadingState(
         }
     }
 }
-