ProductAccessoryFacade (and repository) are probably unnecessary

[vitek-rostislav]

Describe the expected outcome of your requested feature

To access product accessories, we currently use ProductAccessoryFacade (resp. ProductAccessoryRepository). It is not possible to access the accessories directly from a product. In ProductDataFactory, there is the following code:

protected function getAccessoriesData(Product $product)
    {
        $productAccessoriesByPosition = [];
        foreach ($this->productAccessoryRepository->getAllByProduct($product) as $productAccessory) {
            $productAccessoriesByPosition[$productAccessory->getPosition()] = $productAccessory->getAccessory();
        }

        return $productAccessoriesByPosition;
    }

It seems like all of that is unnecessary, as we can do the following changes:

1. Add relation to Product:

    /**
     * @var \Doctrine\Common\Collections\Collection<int, \Shopsys\FrameworkBundle\Model\Product\Accessory\ProductAccessory>
     * @ORM\OneToMany(targetEntity="Shopsys\FrameworkBundle\Model\Product\Accessory\ProductAccessory", mappedBy="product")
     */
    protected Collection $productAccessories;

   /**
     * @return  \Shopsys\FrameworkBundle\Model\Product\Product[]
     */
    public function getAccessoryProductsIndexedByPosition(): array
    {
        $accessoryProducts = [];
        foreach ($this->productAccessories as $productAccessory) {
            $accessoryProducts[$productAccessory->getPosition()] = $productAccessory->getAccessory();
        }

        return $accessoryProducts;
    }

2. add inverseBy setting to ProductAccessory::$product:

/**
     * @var \App\Model\Product\Product
-    * @ORM\ManyToOne(targetEntity="Shopsys\FrameworkBundle\Model\Product\Product")
+    * @ORM\ManyToOne(targetEntity="Shopsys\FrameworkBundle\Model\Product\Product", inversedBy="productAccessories")
     * @ORM\JoinColumn(nullable=false, name="product_id", referencedColumnName="id", onDelete="CASCADE")
     * @ORM\Id
     */
    protected $product;

3. initialize and set the relation in Product::setData() method:

$this->productAccessories = new ArrayCollection($productData->accessories);

Btw in ProductFacade, there is quite a complicated method refreshProductAccessories that is called in create and edit methods. I am not sure, maybe this one can be removed as well