The `use_helpers` method was added in ViewComponent 3.8.0, and it's
included by default in all components since version 3.11.0.
Note we sometimes delegated the `can?` method to the controller instead
of the helpers, for no particularly reason. We're unifying that code as
well.
We forgot to change the line rendering the image in commits 3574bf867c
and 810bdae37a, and so the custom image was being ignored.
Note that, in the test, we're stubbing a constant instead of adding a
new image. The main reason is that, if we add a new image, forks would
have to change the image when they change the `VALID_IMAGES` constant;
otherwise the tests would fail.
