added product model and repo

src/main/java/ntnu/idatt2016/v233/SmartMat/model/product/Product.java

+package ntnu.idatt2016.v233.SmartMat.model.product;
+
+/**
+ * Product is a record class representing a product in the system.
+ * All other info about the product is fetched from api call on fronted.
+ * this ensures that the product is always up to date.
+ * @author Birk
+ * @version 1.0
+ * @since 04.04.2023
+ */
+public record Product (int ean, String name, String description){
+}

src/main/java/ntnu/idatt2016/v233/SmartMat/repository/ProductRepository.java

+package ntnu.idatt2016.v233.SmartMat.repository;
+
+import ntnu.idatt2016.v233.SmartMat.model.ShoppingList;
+import ntnu.idatt2016.v233.SmartMat.model.product.Product;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * Repository for Products
+ * @author Birk
+ * @version 1.0
+ * @since 04.04.2023
+ */
+public interface ProductRepository {
+    /**
+     * Saves a Product to the database
+     *
+     * @param product Product to save
+     */
+    Product save (Product product);
+
+    /**
+     * Gets a Product by its ID
+     *
+     * @param id the ID of the product
+     * @return an optional containing the product if it exists
+     */
+    Optional<Product> getById(int id);
+
+    /**
+     * Gets a Product by name
+     *
+     * @param id the ID of the group
+     * @return an optional containing the product if it exists
+     */
+    Optional<Product> getByProductName(int id);
+
+    /**
+     * Gets all Products
+     *
+     * @return an optional containing a list of all products
+     */
+    Optional<List<Product>> getAll();
+
+
+    /**
+     * Deletes a product by its ID
+     *
+     * @param id the ID of the Product
+     */
+    void deleteById(int id);
+
+}