created different models

lib/models/ingredient_list_entry.dart

@@ -0,0 +1,11 @@
+import 'ingredient.dart';
+import 'unit.dart';
+
+class IngredientListEntry {
+  final Ingredient ingredient;
+  final int amount;
+  final Unit unit;
+  final bool optional;
+
+  IngredientListEntry(this.ingredient, this.amount, this.unit, this.optional);
+}