ba03948dd2
Previously, BKE level preview image code was in `BKE_icons.h` and `icons.hh`. While these types are related, I always found this quite hard to navigate since preview image stuff was just in the middle of icon functions. Plus, people don't expect preview image functions in icon files, the relationship is not obvious. Instead, use focused files that make it easy to quickly navigate them and see what they are dealing with. Pull Request: https://projects.blender.org/blender/blender/pulls/111709