Client implementation of Mercadona Products

[QuinoCode]

(Corresponding Taiga task -> https://prizo.quinovr.es/project/prizo/task/37)
There's need for the client implementation for the retrieval of Mercadona Items.
This will be done following the same structure as seen in other finders such as CarrefourFinder etc but changing the provided API to the one that holds the database for Mercadona Products.

Each obtained product must be a dictionary with the following fields:
{
String id_product;
String name;
String picture_front;
String picture_back;
double price;
double price_measure;
String brand;
bool offer;
double offer_price;
double offer_price_measure;
String category;
String subcategory;
String supermarket;
int contains_milk;
int contains_gluten;
int contains_nuts;
int kcalories;
double fat;
double saturated_fat;
double carbohydrates;
double sugar;
double proteines;
double fiber;
double salt;
}

A request to the provided API will result in a dictionary such as the following:
{ "results": [List with dictionaries containing the parameters requested above with the exact same names]}