Remove consensus/types re-exports (#8540)

There are certain crates which we re-export within `types` which creates a fragmented DevEx, where there are various ways to import the same crates.

```rust
// consensus/types/src/lib.rs
pub use bls::{
AggregatePublicKey, AggregateSignature, Error as BlsError, Keypair, PUBLIC_KEY_BYTES_LEN,
PublicKey, PublicKeyBytes, SIGNATURE_BYTES_LEN, SecretKey, Signature, SignatureBytes,
get_withdrawal_credentials,
};
pub use context_deserialize::{ContextDeserialize, context_deserialize};
pub use fixed_bytes::FixedBytesExtended;
pub use milhouse::{self, List, Vector};
pub use ssz_types::{BitList, BitVector, FixedVector, VariableList, typenum, typenum::Unsigned};
pub use superstruct::superstruct;
```

This PR removes these re-exports and makes it explicit that these types are imported from a non-`consensus/types` crate.


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

lcli/src/generate_bootnode_enr.rs

@@ -1,4 +1,5 @@
 use clap::ArgMatches;
+use fixed_bytes::FixedBytesExtended;
 use lighthouse_network::{
     NETWORK_KEY_FILENAME, NetworkConfig,
     discovery::{CombinedKey, ENR_FILENAME, build_enr},
@@ -9,7 +10,7 @@ use std::io::Write;
 use std::path::PathBuf;
 use std::{fs, net::Ipv4Addr};
 use std::{fs::File, num::NonZeroU16};
-use types::{ChainSpec, EnrForkId, Epoch, EthSpec, FixedBytesExtended, Hash256};
+use types::{ChainSpec, EnrForkId, Epoch, EthSpec, Hash256};
 
 pub fn run<E: EthSpec>(matches: &ArgMatches, spec: &ChainSpec) -> Result<(), String> {
     let ip: Ipv4Addr = clap_utils::parse_required(matches, "ip")?;