The icon component path is defined by SVG files located at {install_location}/data/modules/com.inductiveautomation.perspective/icons/
We currently ship with material.svg which contains all the svgs here https://material.io/tools/icons/?style=baseline
What’s nice is that if you copy the material.svg format, you may add your own collection of svgs by placing the file in the same directory as material.svg.
Then the path of the icon is {svg_file_name}/{icon} just like material/insert_emoticon
Alternatively, judging by your other thread, if you are just doing simple shapes you should be able to just save an svg to your desktop and drag and drop that svg right into the view you are using.