Bevy_ui outlines should respect BorderRadius.

[viridia]

Not a huge priority, but it would be more visually consistent if the outlines also had rounded corners like the entity being outlined. Given that the infrastructure for rounded corners is already in place, I don't imagine that this would be too difficult, and in fact would be simpler because outlines are monocolored, and don't need to handle the alpha-blending between background color and border color.