Restore CameraThumbsCtrl class to manage and cache thumbnails from camera (concept from 2.x serie, dropped with 3.x model view port)
It cache Camera thumb in max size and pass to thumb model pixmap which need to ne resized. No need to reload thumb from camera if thumb size is changed.
This take a lot of time.
This controler is also used in CameMessageBox to confirm which images to remove from camera. This message box is also restored (fdropped in same condition with 3.x serie)
Note: This controller have been moved as well to ImportThumnailModel class which have been a wrong idea. This implementation must be separated and shared with class tht needs cached thumbnails.
ImportThumnailModel use this controller directly which simplify a lots implementation.