Support for sly CLI (easily add radix icons)

[kentcdodds]

Shout-out to @jacobparis for creating @sly-cli/sly: https://sly-cli.fly.dev/

Jacob also added this to the Epic Stack: #332

The documentation for adding icons has been updated: https://github.com/epicweb-dev/epic-stack/blob/main/docs/icons.md

This could also be used to manage shadcn as well possibly. Very cool!