CORE-4164 Removed nav. folder delete logic from presenter.

Updated DiskResourcePresenterImpl::doDelete to only handle logic for deleting resources selected in the center grid panel.
The ability to delete folders from the navigation panel was removed in commit e2688df47309866004f33c6c5e660ca1c40205e1.
CORE-3509 Re-added trash delete confirmation.

Added a confirmation dialog to DiskResourcePresenterImpl::doDelete when the user attempts to delete items from the trash.