Rollup merge of #146675 - Jules-Bertholet:sync-nonexclusive, r=Mark-Simulacrum

Allow shared access to `Exclusive<T>` when `T: Sync`

Addresses libs-api request in rust-lang/rust#98407 (comment).

Adds the following trait impls to `Exclusive<T>`, all bounded on `T: Sync`:

- `AsRef<T>`
- `Clone`
- `Copy`
- `PartialEq`
- `StructuralPartialEq`
- `Eq`
- `Hash`
- `PartialOrd`
- `Ord`
- `Fn`

``@rustbot`` label T-libs-api

Author: matthiaskrgr