added provider for recipe wizard

lib/models/ingredient.dart

@@ -13,4 +13,12 @@ class Ingredient {
     this.possibleUnits = const [],
     this.preferredBrands = const [],
   });
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Ingredient && other.title == title && other.type == type;
+
+  @override
+  int get hashCode => Object.hash(title, type);
 }