added simple recipeProvider

lib/services/providers/recipe_provider.dart

@@ -0,0 +1,19 @@
+import 'package:flutter/material.dart';
+
+import '../../models/recipe.dart';
+
+class RecipeProvider extends ChangeNotifier {
+  Recipe? _selectedRecipe;
+
+  Recipe? get selectedRecipe => _selectedRecipe;
+
+  set selectedRecipe(Recipe? recipe) {
+    _selectedRecipe = recipe;
+    notifyListeners();
+  }
+
+  void clearRecipe() {
+    _selectedRecipe = null;
+    notifyListeners();
+  }
+}