[Backport to 11.2] Horizontal scrolling not possible in document overview

It's not possible to scroll horizontally in the document overview. Because we have extra columns because of plugins scrolling is required on smaller screen sizes. With the current implementation the columns at the right and the paging label are not visible for everyone (e.g. Firefox 100% zoom level with a 1920 x 1200 resolution). Though in the demo project there is no issue the document overview should be flexible in supporting extra columns.