Refactor consensus/types (#7827)

Organize and categorize `consensus/types` into modules based on their relation to key consensus structures/concepts.
This is a precursor to a sensible public interface.

While this refactor is very opinionated, I am open to suggestions on module names, or type groupings if my current ones are inappropriate.


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

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -74,6 +74,7 @@ use crate::{
     AvailabilityPendingExecutedBlock, BeaconChainError, BeaconForkChoiceStore, BeaconSnapshot,
     CachedHead, metrics,
 };
+use eth2::beacon_response::ForkVersionedResponse;
 use eth2::types::{
     EventKind, SseBlobSidecar, SseBlock, SseDataColumnSidecar, SseExtendedPayloadAttributes,
 };