[Radar] add IRR AS-SET lookup endpoint

[digizeph]

Summary

• [Radar] add IRR AS-SET lookup endpoint

Screenshots (optional)

Documentation checklist

• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• The documentation style guide has been adhered to.