Adjust file picker / activity chooser forms to full screen popup.

Forms need to be tweaked to be usable on the new full screen popup.

List of elements to tweak:

• the details view/list view/folder view icons could be a bit bigger, easier to touch.
• the label / input should be displayed at a reasonable distance of the border
• there should be a bar/separation between the last selected repository and the repository form top bar.