Our help documents are unfinished, and we shouldn't ship
unfinished documentation in our initial release.
We can revert this commit when we're ready to write the
documents properly.
Part-of: <https://gitlab.gnome.org/Incubator/loupe/-/merge_requests/156>
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.