Update to the latest Serai Substrate (#125)

* Update to the latest Serai Substrate

* Add Protobuf to build dependencies

Docker shouldn't need updating as this should've been added to the image 
in 
2dbace5b01.

* Get substrate to build

* Correct protoc build step

* Remove the benchmarking code

There's some macro resolution error that isn't apparent. I worked on it 
for about half an hour but...

* Remove unnecessary clone

* Correct runtime-benchmarks flag usage

substrate/node/src/service.rs

@@ -96,7 +96,7 @@ pub fn new_full(config: Configuration) -> Result<TaskManager, ServiceError> {
     transaction_pool,
   } = new_partial(&config)?;
 
-  let (network, system_rpc_tx, network_starter) =
+  let (network, system_rpc_tx, tx_handler_controller, network_starter) =
     sc_service::build_network(sc_service::BuildNetworkParams {
       config: &config,
       client: client.clone(),
@@ -142,6 +142,7 @@ pub fn new_full(config: Configuration) -> Result<TaskManager, ServiceError> {
     rpc_builder: rpc_extensions_builder,
     backend,
     system_rpc_tx,
+    tx_handler_controller,
     config,
     telemetry: telemetry.as_mut(),
   })?;