Support sending and receiving multiple Justifications (#8266)

* client/network: support sending multiple justifications

* network: flag support for multiple justifications in protobuf request

* Update client/network/src/protocol.rs

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

* network: update comment on protobuf field

Co-authored-by: Pierre Krieger <pierre.krieger1708@gmail.com>

substrate/client/network/src/light_client_requests/sender.rs

@@ -722,6 +722,7 @@ impl<B: Block> Request<B> {
 					to_block: Default::default(),
 					direction: schema::v1::Direction::Ascending as i32,
 					max_blocks: 1,
+					support_multiple_justifications: true,
 				};
 
 				let mut buf = Vec::with_capacity(rq.encoded_len());