[Enhancement] Add a configuration option to open bitstream download in new browser tabs.

## Is your feature request related to a problem? Please describe.

By default bitstreams on item pages are opened in the same page of the item.
We should add the possibility to configure this behavior and allow the bitstreams to be opened also in a new tab.

## Describe the solution you'd like

Add a configuration to allow opening bitstreams link in item page in a new tab.

