Add feature flag to enable v2 assignments (#2444)

Scaffold everything, so that we can enable v2 assignments via a node
feature bit, once all nodes have upgraded to the new protocol.

Implements: https://github.com/paritytech/polkadot-sdk/issues/628

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

polkadot/node/network/availability-distribution/src/pov_requester/mod.rs

@@ -146,7 +146,9 @@ mod tests {
 		AllMessages, AvailabilityDistributionMessage, RuntimeApiMessage, RuntimeApiRequest,
 	};
 	use polkadot_node_subsystem_test_helpers as test_helpers;
-	use polkadot_primitives::{CandidateHash, ExecutorParams, Hash, ValidatorIndex};
+	use polkadot_primitives::{
+		vstaging::NodeFeatures, CandidateHash, ExecutorParams, Hash, ValidatorIndex,
+	};
 	use test_helpers::mock::make_ferdie_keystore;
 
 	use super::*;
@@ -214,6 +216,12 @@ mod tests {
 					)) => {
 						tx.send(Ok(Some(ExecutorParams::default()))).unwrap();
 					},
+					AllMessages::RuntimeApi(RuntimeApiMessage::Request(
+						_,
+						RuntimeApiRequest::NodeFeatures(_, si_tx),
+					)) => {
+						si_tx.send(Ok(NodeFeatures::EMPTY)).unwrap();
+					},
 					AllMessages::NetworkBridgeTx(NetworkBridgeTxMessage::SendRequests(
 						mut reqs,
 						_,

polkadot/node/network/availability-distribution/src/requester/tests.rs

@@ -25,8 +25,8 @@ use polkadot_node_primitives::{BlockData, ErasureChunk, PoV};
 use polkadot_node_subsystem_test_helpers::mock::new_leaf;
 use polkadot_node_subsystem_util::runtime::RuntimeInfo;
 use polkadot_primitives::{
-	BlockNumber, CoreState, ExecutorParams, GroupIndex, Hash, Id as ParaId, ScheduledCore,
-	SessionIndex, SessionInfo,
+	vstaging::NodeFeatures, BlockNumber, CoreState, ExecutorParams, GroupIndex, Hash, Id as ParaId,
+	ScheduledCore, SessionIndex, SessionInfo,
 };
 use sp_core::traits::SpawnNamed;
 
@@ -125,6 +125,10 @@ fn spawn_virtual_overseer(
 								tx.send(Ok(Some(ExecutorParams::default())))
 									.expect("Receiver should be alive.");
 							},
+							RuntimeApiRequest::NodeFeatures(_, tx) => {
+								tx.send(Ok(NodeFeatures::EMPTY))
+									.expect("Receiver should be alive.");
+							},
 							RuntimeApiRequest::AvailabilityCores(tx) => {
 								let para_id = ParaId::from(1_u32);
 								let maybe_block_position =

polkadot/node/network/availability-distribution/src/tests/state.rs

@@ -46,8 +46,8 @@ use polkadot_node_subsystem::{
 };
 use polkadot_node_subsystem_test_helpers as test_helpers;
 use polkadot_primitives::{
-	CandidateHash, CoreState, ExecutorParams, GroupIndex, Hash, Id as ParaId, ScheduledCore,
-	SessionInfo, ValidatorIndex,
+	vstaging::NodeFeatures, CandidateHash, CoreState, ExecutorParams, GroupIndex, Hash,
+	Id as ParaId, ScheduledCore, SessionInfo, ValidatorIndex,
 };
 use test_helpers::mock::{make_ferdie_keystore, new_leaf};
 
@@ -264,6 +264,9 @@ impl TestState {
 							tx.send(Ok(Some(ExecutorParams::default())))
 								.expect("Receiver should be alive.");
 						},
+						RuntimeApiRequest::NodeFeatures(_, si_tx) => {
+							si_tx.send(Ok(NodeFeatures::EMPTY)).expect("Receiver should be alive.");
+						},
 						RuntimeApiRequest::AvailabilityCores(tx) => {
 							gum::trace!(target: LOG_TARGET, cores= ?self.cores[&hash], hash = ?hash, "Sending out cores for hash");
 							tx.send(Ok(self.cores[&hash].clone()))