xtask: Add validation layer for GPUI commands (#64869)

## Summary

This PR adds a validation step to the GPUI publishing plan, ensuring
that crates there have proper licenses and that we do not face duplicate
crate names (this one is acutally currently violated but something to
fix separately).

Release Notes:

- N/A
447f72e516Finn Evers committed on 9/28/2026, 2:38:57 PM· committed by GitHubparent1b572a2
6 files changedLine totals unavailable