Allow pagination for simple select from URL

[fdyckhoff]

For large list of options it would be nice to allow pagination für the simple select search results.

To achieve this a page parameter needs to be added to the URL.

The Select2JsonResponse should also return information about the current pagination.

The initial request on page load to get the labels of the current selected options for a product should add the selected value to the URL or the product field may not be able to resolve labels for options on the second page or later.