Rollup merge of #82487 - CDirkx:const-socketaddr, r=m-ou-se

Constify methods of `std::net::SocketAddr`, `SocketAddrV4` and `SocketAddrV6`

The following methods are made unstable const under the `const_socketaddr` feature (https://github.com/rust-lang/rust/issues/82485):

```rust
// std::net

impl SocketAddr {
    pub const fn ip(&self) -> IpAddr;
    pub const fn port(&self) -> u16;
    pub const fn is_ipv4(&self) -> bool;
    pub const fn is_ipv6(&self) -> bool;
}

impl SocketAddrV4 {
    pub const fn ip(&self) -> IpAddr;
    pub const fn port(&self) -> u16;
}

impl SocketAddrV6 {
    pub const fn ip(&self) -> IpAddr;
    pub const fn port(&self) -> u16;
    pub const fn flowinfo(&self) -> u32;
    pub const fn scope_id(&self) -> u32;
}
```

Note: `SocketAddrV4::ip` and `SocketAddrV6::ip` use pointer casting and depend on the unstable feature `const_raw_ptr_deref`

library/std/src/lib.rs

@@ -249,6 +249,7 @@
 #![feature(const_ip)]
 #![feature(const_ipv6)]
 #![feature(const_raw_ptr_deref)]
+#![feature(const_socketaddr)]
 #![feature(const_ipv4)]
 #![feature(container_error_extra)]
 #![feature(core_intrinsics)]