Cleanup consensus/types re-exports (#8643)

Removes some of the temporary re-exports in `consensus/types`.

I am doing this in multiple parts to keep each diff small.


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

beacon_node/http_api/tests/tests.rs

@@ -44,7 +44,7 @@ use std::convert::TryInto;
 use std::sync::Arc;
 use tokio::time::Duration;
 use tree_hash::TreeHash;
-use types::application_domain::ApplicationDomain;
+use types::ApplicationDomain;
 use types::{
     Domain, EthSpec, ExecutionBlockHash, Hash256, MainnetEthSpec, RelativeEpoch, SelectionProof,
     SignedRoot, SingleAttestation, Slot, attestation::AttestationBase,