Cell Dissemination (Partial messages) (#8314)

- https://github.com/ethereum/consensus-specs/pull/4558
- https://eips.ethereum.org/EIPS/eip-8136


  


Co-Authored-By: Daniel Knopik <daniel@dknopik.de>

Co-Authored-By: Pawan Dhananjay <pawandhananjay@gmail.com>

Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>

beacon_node/execution_layer/src/engine_api/json_structures.rs

@@ -864,6 +864,9 @@ pub struct BlobAndProof<E: EthSpec> {
     pub proofs: KzgProofs<E>,
 }
 
+/// A BlobAndProofV3 is just a BlobAndProofV2 that may also be `null` if unknown by the EL.
+pub type BlobAndProofV3<E> = Option<BlobAndProofV2<E>>;
+
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct JsonForkchoiceStateV1 {