[WebFlux - Warehouse] Make sure the sequence generator is used for the primary key in Warehouse project

[thepassenger-hub]

Since we didn't override the save method in the product repository, we don't know how the primary key is inserted (sequence, table incremental, etc...). Due to the fact that more tables will be added in the future, we should make sure the pk_sequence inserted in the schema is the one used to generate the pk. In MVC this was done with the @Generator annotation, in WebFlux the annotation doesn't exist so we may need to add the query @query("INSERT into product(id,....) VALUES (NEXTVAL(pk_sequence),....)")