Support conversion from grpc response to beacon block

.gitignore

@@ -1,3 +1,5 @@
 /target
 
 Cargo.lock
+
+.DS_Store

src/lib.rs

@@ -198,7 +198,10 @@ pub mod firehose {
 pub mod beacon {
     pub mod r#type {
         pub mod v1 {
-            use crate::{firehose::v2::SingleBlockResponse, ProtosError};
+            use crate::{
+                firehose::v2::{Response, SingleBlockResponse},
+                ProtosError,
+            };
             use primitive_types::{H256, U256};
             use prost::Message;
             use ssz_types::{length::Fixed, Bitfield, FixedVector};
@@ -545,6 +548,16 @@ pub mod beacon {
                 }
             }
 
+            impl TryFrom<Response> for Block {
+                type Error = ProtosError;
+
+                fn try_from(response: Response) -> Result<Self, Self::Error> {
+                    let any = response.block.ok_or(ProtosError::NullBlock)?;
+                    let block = Block::decode(any.value.as_ref())?;
+                    Ok(block)
+                }
+            }
+
             impl<E: EthSpec> TryFrom<SyncAggregate> for types::SyncAggregate<E> {
                 type Error = ProtosError;