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>

common/validator_dir/src/builder.rs

@@ -1,5 +1,5 @@
 use crate::{Error as DirError, ValidatorDir};
-use bls::get_withdrawal_credentials;
+use bls::{Keypair, Signature, get_withdrawal_credentials};
 use deposit_contract::{Error as DepositError, encode_eth1_tx_data};
 use eth2_keystore::{Error as KeystoreError, Keystore, KeystoreBuilder, PlainText};
 use filesystem::create_with_600_perms;
@@ -7,7 +7,7 @@ use rand::{Rng, distr::Alphanumeric};
 use std::fs::{File, create_dir_all};
 use std::io::{self, Write};
 use std::path::{Path, PathBuf};
-use types::{ChainSpec, DepositData, Hash256, Keypair, Signature};
+use types::{ChainSpec, DepositData, Hash256};
 
 /// The `Alphanumeric` crate only generates a-z, A-Z, 0-9, therefore it has a range of 62
 /// characters.