Auto merge of #116949 - hamza1311:stablize-arc_unwrap_or_clone, r=dtolnay

Stablize arc_unwrap_or_clone

Fixes: #93610

This likely needs FCP. I created this PR as it's stabilization is trivial and FCP can be just conducted here. Not sure how to ping the libs API team (last attempt didn't work apparently according to GH UI)

Author: bors