This will make writing libadwaita-based code a bit
nicer, and make it nicer when we use crates that
libadwaita's API re-exports.
Also clean up the unused imports exposed by
this change.
This commit adds directory navigation to Image Viewer.
Currently it only sorts images by name, instead of following
directory sorting like the mockups.
The initial commit of gnome-image-viewer.
Things are in an MVP state, with image viewing and
opening from the desktop functional. We also can
open images externally, print them, and set them as
backgrounds.
