Use new SVG icons in place of current "Alert" icons, used on dialogs
and confirmations. No need for alert_icons.svg, alert_icons.png,
alert_icons_update.py. Also looks better as they are made at exact
requested size instead of 256x256 then scaled down to display.
Pull Request: https://projects.blender.org/blender/blender/pulls/123786
5c377686e7