Support custom vector icons

Blender renders it's native UI icons as vectors. They can scale to any size and look crisp.

It would be useful to be able to use the same UI rendering when adding custom icons. Interface scaling above 2.0 makes the traditional way of adding custom icons look blurry in comparison: These icons are added using a similar approach to this example docs.blender.org/api/current/bpy.utils.previews.html

A way to supply SVGs to "icon_value" in UI elements would be amazing for add-on developers.