Implement PeerDAS RPC handlers (#6237)

* Implement PeerDAS RPC handlers

* use terminate_response_stream

* Merge branch 'unstable' of https://github.com/sigp/lighthouse into peerdas-network-rpc-handler

* cargo fmt

beacon_node/lighthouse_network/src/rpc/methods.rs

@@ -6,6 +6,7 @@ use serde::Serialize;
 use ssz::Encode;
 use ssz_derive::{Decode, Encode};
 use ssz_types::{typenum::U256, VariableList};
+use std::collections::BTreeMap;
 use std::fmt::Display;
 use std::marker::PhantomData;
 use std::ops::Deref;
@@ -426,6 +427,17 @@ impl DataColumnsByRootRequest {
     pub fn new_single(block_root: Hash256, index: ColumnIndex, spec: &ChainSpec) -> Self {
         Self::new(vec![DataColumnIdentifier { block_root, index }], spec)
     }
+
+    pub fn group_by_ordered_block_root(&self) -> Vec<(Hash256, Vec<ColumnIndex>)> {
+        let mut column_indexes_by_block = BTreeMap::<Hash256, Vec<ColumnIndex>>::new();
+        for request_id in self.data_column_ids.as_slice() {
+            column_indexes_by_block
+                .entry(request_id.block_root)
+                .or_default()
+                .push(request_id.index);
+        }
+        column_indexes_by_block.into_iter().collect()
+    }
 }
 
 /* RPC Handling and Grouping */