Sort does not work with setFilterDateRange

[radek-bryknar]

reproduction steps:

$grid->setSortable();
$grid->setSortableHandler();

$grid->addColumnDateTime('endTimestamp', 'end_timestamp')
		->setFilterDateRange();

When FilterDateRange is included in grid, sort does not work. Alert with undefined showed up.

when I spect network query params it says undefined.

Without ->setFilterDateRange() everything works fine.

[Radim Vaculík]

@radek-bryknar Could you have a look into it, please? And send a PR? 🙏