Improve transport connection errors (#4540)

## Issue Addressed

#4538 

## Proposed Changes

add newtype wrapper around DialError that extracts error messages and logs them in a more readable format

## Additional Info

I was able to test Transport Dial Errors in the situation where a libp2p instance attempts to ping a nonexistent peer. That error message should look something like

`A transport level error has ocurred: Connection refused (os error 61)`

AgeManning mentioned we should try fetching only the most inner error (in situations where theres a nested error). I took a stab at implementing that

For non transport DialErrors, I wrote out the error messages explicitly (as per the docs). Could potentially clean things up here if thats not necessary


Co-authored-by: Age Manning <Age@AgeManning.com>

beacon_node/lighthouse_network/src/discovery/mod.rs

@@ -7,9 +7,9 @@ pub(crate) mod enr;
 pub mod enr_ext;
 
 // Allow external use of the lighthouse ENR builder
-use crate::metrics;
 use crate::service::TARGET_SUBNET_PEERS;
 use crate::{error, Enr, NetworkConfig, NetworkGlobals, Subnet, SubnetDiscovery};
+use crate::{metrics, ClearDialError};
 use discv5::{enr::NodeId, Discv5, Discv5Event};
 pub use enr::{
     build_enr, create_enr_builder_from_config, load_enr_from_disk, use_or_load_enr, CombinedKey,
@@ -1111,7 +1111,7 @@ impl<TSpec: EthSpec> Discovery<TSpec> {
                 | DialError::Transport(_)
                 | DialError::WrongPeerId { .. } => {
                     // set peer as disconnected in discovery DHT
-                    debug!(self.log, "Marking peer disconnected in DHT"; "peer_id" => %peer_id);
+                    debug!(self.log, "Marking peer disconnected in DHT"; "peer_id" => %peer_id, "error" => %ClearDialError(error));
                     self.disconnect_peer(&peer_id);
                 }
                 DialError::DialPeerConditionFalse(_) | DialError::Aborted => {}