Rollup merge of #104252 - faern:stabilize-const_socketaddr, r=JohnTitor

Stabilize the const_socketaddr feature

Stabilizes `#![feature(const_socketaddr)]`. Tracking issue: #82485
Closes #82485

This has been unstably const for over a year now. And the code change simplifying the constness of the `new` constructors has been in stable Rust since 1.64 (a bit over a full release cycle). I'm not aware of any blockers to this stabilization.