[select] Keep focus indicator on trigger when popup is open

# Feature request

## Summary

Currently, when popup is open, the trigger loses focus. I need to keep trigger indicating it is focused (with outline) on popup open. It doesn't have to maintain "physical" focus, just some data-attribute could be handy to style the trigger properly.

I have made some workarounds using onOpenChangeComplete, but the trigger outline still flickers, when using transitions and animations when closing popup.

https://github.com/user-attachments/assets/daca159b-898e-42b4-8d3b-d0430ee8a5b9