Add toledo support (#1874)

## Issue Addressed

NA

## Proposed Changes

Adds support for the [Toledo](https://github.com/protolambda/toledo) dev-net.

```bash
lighthouse --testnet toledo bn --http
```

This is for development only, we do not recommend users to join this testnet.

## Additional Info

- ~~Blocked on #1862~~

common/eth2_config/src/lib.rs

@@ -124,6 +124,8 @@ define_net!(zinken, include_zinken_file, "zinken", true);
 
 define_net!(mainnet, include_mainnet_file, "mainnet", false);
 
+define_net!(toledo, include_toledo_file, "toledo", true);
+
 #[cfg(test)]
 mod tests {
     use super::*;