Add button to keep only one of the files

[johnnyasantoss]

Description
In order to remove many duplicates from a group there should be a button on the photo/video card to keep only that one. Clicking on this button would delete the other duplicates and close the current group (optimistically)

If you have a group with many duplicates its really tedious to go over them, also, clicking delete on each is not helpful as they vanish and change the visual layout of the group, leading to missclicks and errors.