Use if-addrs instead of local_ip_address (#8659)

Swaps out the `local_ip_address` dependency for `if-addrs`. The reason for this is that is that `local_ip_address` is a relatively heavy dependency (depends on `neli`) compared to `if-addrs` and we only use it to check the presence of an IPv6 interface. This is an experiment to see if we can use the more lightweight `if-addrs` instead.


Co-Authored-By: Mac L <mjladson@pm.me>

beacon_node/lighthouse_network/src/config.rs

@@ -5,8 +5,8 @@ use crate::{Enr, PeerIdSerialized};
 use directory::{
     DEFAULT_BEACON_NODE_DIR, DEFAULT_HARDCODED_NETWORK, DEFAULT_NETWORK_DIR, DEFAULT_ROOT_DIR,
 };
+use if_addrs::get_if_addrs;
 use libp2p::{Multiaddr, gossipsub};
-use local_ip_address::local_ipv6;
 use network_utils::listen_addr::{ListenAddr, ListenAddress};
 use serde::{Deserialize, Serialize};
 use sha2::{Digest, Sha256};
@@ -262,13 +262,13 @@ impl Config {
     /// A helper function to check if the local host has a globally routeable IPv6 address. If so,
     /// returns true.
     pub fn is_ipv6_supported() -> bool {
-        // If IPv6 is supported
-        let Ok(std::net::IpAddr::V6(local_ip)) = local_ipv6() else {
+        let Ok(addrs) = get_if_addrs() else {
             return false;
         };
 
-        // If its globally routable, return true
-        is_global_ipv6(&local_ip)
+        addrs.iter().any(
+            |iface| matches!(iface.addr, if_addrs::IfAddr::V6(ref v6) if is_global_ipv6(&v6.ip)),
+        )
     }
 
     pub fn listen_addrs(&self) -> &ListenAddress {