Product creatorId changes when updating categories as admin

[henriquecbuss]

As part of our new shop update with categories, we're going to allow community admins to edit the categories from products in the shop. This is being implemented in https://github.com/cambiatus/frontend/pull/805.

However, when submitting a product mutation as the admin of the community, the creatorId field of the product changes from the previous owner to the community admin.

For example: I edited the categories of a product created by @lucca65 on the Buss community. The mutation was something like this (these aren't the correct category ids):

mutation {
  product(id: 72, categories: [1, 2, 3]) {
    id
  }
}

And now, after submitting that mutation, the product belongs to me instead of @lucca65 (who created the product)