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>

beacon_node/beacon_chain/tests/schema_stability.rs

@@ -4,6 +4,7 @@ use beacon_chain::{
     persisted_custody::PersistedCustody,
     test_utils::{BeaconChainHarness, DiskHarnessType, test_spec},
 };
+use bls::Keypair;
 use logging::create_test_tracing_subscriber;
 use operation_pool::PersistedOperationPool;
 use ssz::Encode;
@@ -16,7 +17,7 @@ use store::{
 };
 use strum::IntoEnumIterator;
 use tempfile::{TempDir, tempdir};
-use types::{ChainSpec, Hash256, Keypair, MainnetEthSpec, Slot};
+use types::{ChainSpec, Hash256, MainnetEthSpec, Slot};
 
 type E = MainnetEthSpec;
 type Store<E> = Arc<HotColdDB<E, BeaconNodeBackend<E>, BeaconNodeBackend<E>>>;