Ref https://github.com/svg/svgo/issues/1499
- migrated to visitor plugin api
- covered with tsdoc
- made the plugin idempotent as requested a few times
Now even manually running svgo a few times will not duplicate
prefix in ids and classes
- run each plugin test twice to see which plugin need to run many times
ideally idempotent plugins will allow to get rid of multipass option in v3
