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/lighthouse_network/src/rpc/codec.rs

@@ -8,7 +8,7 @@ use libp2p::bytes::BytesMut;
 use snap::read::FrameDecoder;
 use snap::write::FrameEncoder;
 use ssz::{Decode, Encode};
-use ssz_types::VariableList;
+use ssz_types::{RuntimeVariableList, VariableList};
 use std::io::Cursor;
 use std::io::ErrorKind;
 use std::io::{Read, Write};
@@ -18,10 +18,10 @@ use tokio_util::codec::{Decoder, Encoder};
 use types::{
     BlobSidecar, ChainSpec, DataColumnSidecar, DataColumnsByRootIdentifier, EthSpec, ForkContext,
     ForkName, Hash256, LightClientBootstrap, LightClientFinalityUpdate,
-    LightClientOptimisticUpdate, LightClientUpdate, RuntimeVariableList, SignedBeaconBlock,
-    SignedBeaconBlockAltair, SignedBeaconBlockBase, SignedBeaconBlockBellatrix,
-    SignedBeaconBlockCapella, SignedBeaconBlockDeneb, SignedBeaconBlockElectra,
-    SignedBeaconBlockFulu, SignedBeaconBlockGloas,
+    LightClientOptimisticUpdate, LightClientUpdate, SignedBeaconBlock, SignedBeaconBlockAltair,
+    SignedBeaconBlockBase, SignedBeaconBlockBellatrix, SignedBeaconBlockCapella,
+    SignedBeaconBlockDeneb, SignedBeaconBlockElectra, SignedBeaconBlockFulu,
+    SignedBeaconBlockGloas,
 };
 use unsigned_varint::codec::Uvi;