DataTable: make it possible to specify the label for the sorting buttons

[edoardo]

Currently it's a fixed string for all column headers, see: https://github.com/dhis2/ui/blob/01eea9b1a8401a985ca1ff21f280b0a6c6066301/components/table/src/data-table/data-table-column-header/sorter.js#L31

It would be helpful to be able to pass a custom label from the consumer app.