When you turn a LoyaltyCard into a bundle, it writes the files to
storage as it can't otherwise fit in the limited storage size. This
means that, on rotation, you write all images to storage and load them
again. Using a ViewModel prevents that storage hit due to holding it in
memory (as a ViewModel has a longer lifecycle).

This should make it possible to properly cancel the running barcode
generation threads on rotation and prevent CPU rising on many rotations.

This prevents loading the front and back images when scrolling through
the loyalty card list and should allow scaling to more images/files more
easily