[macOS] Icons From Builtin Widgets With Icons Using widget::icon::from_name() Do Not Render

[vkhitrin]

While working to adapt my COSMIC based application (https://github.com/vkhitrin/cosmicding) to support macOS, I have noticed that most of the builtin widgets do not render icons.
As far as I am aware, this occurs due to macOS not having XDG (and cosmic-icons) icons available.

Side note, widget::button::link().trailing_icon(true) is rendered.
(tested on commit https://github.com/pop-os/libcosmic?rev=953685a88267894ea3fa40f2b99139c3c4e784d6#953685a88267894ea3fa40f2b99139c3c4e784d6)

Example:

I am not sure if supporting macOS is in the current scope of libcosmic, but I would like to raise the following questions:

1. For cross-platform systems which do not install cosmic-icons or XDG icons, should we expect the builtin default widgets to render images? For example, the trailing icons works for widget::button::link but checkboxes for widget::menu::MenuItem::CheckBox do not display the check mark.
2. For cross-platform development, should developers bundle their own SVG(s), and provide a custom class for widgets that refers to those SVG(s)?