Final changes for fusaka-devnet-2 (#7655)

Closes #7467.

This PR primarily addresses [the P2P changes](https://github.com/ethereum/EIPs/pull/9840) in [fusaka-devnet-2](https://fusaka-devnet-2.ethpandaops.io/). Specifically:

* [the new `nfd` parameter added to the `ENR`](https://github.com/ethereum/EIPs/pull/9840)
* [the modified `compute_fork_digest()` changes for every BPO fork](https://github.com/ethereum/EIPs/pull/9840)

90% of this PR was absolutely hacked together as fast as possible during the Berlinterop as fast as I could while running between Glamsterdam debates. Luckily, it seems to work. But I was unable to be as careful in avoiding bugs as I usually am. I've cleaned up the things *I remember* wanting to come back and have a closer look at. But still working on this.

Progress:
* [x] get it working on `fusaka-devnet-2`
* [ ] [*optional* disconnect from peers with incorrect `nfd` at the fork boundary](https://github.com/ethereum/consensus-specs/pull/4407) - Can be addressed in a future PR if necessary
* [x] first pass clean-up
* [x] fix up all the broken tests
* [x] final self-review
* [x] more thorough review from people more familiar with affected code

beacon_node/lighthouse_network/src/config.rs

@@ -457,7 +457,7 @@ pub fn gossipsub_config(
     ) -> Vec<u8> {
         let topic_bytes = message.topic.as_str().as_bytes();
 
-        if fork_context.current_fork().altair_enabled() {
+        if fork_context.current_fork_name().altair_enabled() {
             let topic_len_bytes = topic_bytes.len().to_le_bytes();
             let mut vec = Vec::with_capacity(
                 prefix.len() + topic_len_bytes.len() + topic_bytes.len() + message.data.len(),