Add storybooks for file diffs and improve ugly states
Created by: eseliger
For work on campaigns interfaces, I needed those as a storybook as well. While working on it, I realized two things:
- We are inconsistent with the badging for moved files, so I added a badge there as well.
- We always show the diff for deleted files by default, but most codehosts hide those by default (for good reasons, I think), so I added that functionality to ours as well.