libadwaita radiobutton and checkbox styling issues

[ethanc8]

On KDE Plasma Wayland on openSUSE Slowroll, with elementary/stylesheet from git and libadwaita 1.7.6 built from source, I found a few issues while browsing adwaita-1-demo (see #931).

On each screenshot, on the left is io.elementary.stylesheet.lime and on the right is the libadwaita stylesheet, with accent color #288417 applied by kde-gtk-config.

Lists - radiobutton

• The image in the center of the radiobutton is missing.

Style classes - checkboxes

• The checkboxes are missing their interiors, and the selection mode checkboxes are not larger or round.