Add location_id to product data

[StefanoGiu]

I made the below changes to make available the location_id into the product data model:

file: pygrocy\data_models\product.py

I don't know which brench to use for creating a pull request. Can you add the below changes?

def _init_empty(self):
    self._name = None
    self._location_id = None

---

def _init_from_ProductData(self, product: ProductData):
    self._id = product.id
    self._product_group_id = product.product_group_id
    self._name = product.name
    self._location_id = product.location_id

---

@property
def location_id(self) -> str:
    return self._location_id