Dispute distribution implementation (#3282)

* Dispute protocol.

* Dispute distribution protocol.

* Get network requests routed.

* WIP: Basic dispute sender logic.

* Basic validator determination logic.

* WIP: Getting things to typecheck.

* Slightly larger timeout.

* More typechecking stuff.

* Cleanup.

* Finished most of the sending logic.

* Handle active leaves updates

- Cleanup dead disputes
- Update sends for new sessions
- Retry on errors

* Pass sessions in already.

* Startup dispute sending.

* Provide incoming decoding facilities

and use them in statement-distribution.

* Relaxed runtime util requirements.

We only need a `SubsystemSender` not a full `SubsystemContext`.

* Better usability of incoming requests.

Make it possible to consume stuff without clones.

* Add basic receiver functionality.

* Cleanup + fixes for sender.

* One more sender fix.

* Start receiver.

* Make sure to send responses back.

* WIP: Exposed authority discovery

* Make tests pass.

* Fully featured receiver.

* Decrease cost of `NotAValidator`.

* Make `RuntimeInfo` LRU cache size configurable.

* Cache more sessions.

* Fix collator protocol.

* Disable metrics for now.

* Make dispute-distribution a proper subsystem.

* Fix naming.

* Code style fixes.

* Factored out 4x copied mock function.

* WIP: Tests.

* Whitespace cleanup.

* Accessor functions.

* More testing.

* More Debug instances.

* Fix busy loop.

* Working tests.

* More tests.

* Cleanup.

* Fix build.

* Basic receiving test.

* Non validator message gets dropped.

* More receiving tests.

* Test nested and subsequent imports.

* Fix spaces.

* Better formatted imports.

* Import cleanup.

* Metrics.

* Message -> MuxedMessage

* Message -> MuxedMessage

* More review remarks.

* Add missing metrics.rs.

* Fix flaky test.

* Dispute coordinator - deliver confirmations.

* Send out `DisputeMessage` on issue local statement.

* Unwire dispute distribution.

* Review remarks.

* Review remarks.

* Better docs.

polkadot/node/network/bridge/src/tests.rs

@@ -67,7 +67,7 @@ struct TestNetwork {
 	_req_configs: Vec<RequestResponseConfig>,
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 struct TestAuthorityDiscovery;
 
 // The test's view of the network. This receives updates from the subsystem in the form
@@ -688,6 +688,12 @@ fn peer_view_updates_sent_via_overseer() {
 
 		let view = view![Hash::repeat_byte(1)];
 
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::DisputeDistribution(
+				DisputeDistributionMessage::DisputeSendingReceiver(_)
+			)
+		);
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::StatementDistribution(
@@ -740,6 +746,12 @@ fn peer_messages_sent_via_overseer() {
 			ObservedRole::Full,
 		).await;
 
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::DisputeDistribution(
+				DisputeDistributionMessage::DisputeSendingReceiver(_)
+			)
+		);
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::StatementDistribution(
@@ -812,6 +824,12 @@ fn peer_disconnect_from_just_one_peerset() {
 		network_handle.connect_peer(peer.clone(), PeerSet::Validation, ObservedRole::Full).await;
 		network_handle.connect_peer(peer.clone(), PeerSet::Collation, ObservedRole::Full).await;
 
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::DisputeDistribution(
+				DisputeDistributionMessage::DisputeSendingReceiver(_)
+			)
+		);
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::StatementDistribution(
@@ -894,6 +912,12 @@ fn relays_collation_protocol_messages() {
 		let peer_a = PeerId::random();
 		let peer_b = PeerId::random();
 
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::DisputeDistribution(
+				DisputeDistributionMessage::DisputeSendingReceiver(_)
+			)
+		);
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::StatementDistribution(
@@ -992,6 +1016,12 @@ fn different_views_on_different_peer_sets() {
 		network_handle.connect_peer(peer.clone(), PeerSet::Validation, ObservedRole::Full).await;
 		network_handle.connect_peer(peer.clone(), PeerSet::Collation, ObservedRole::Full).await;
 
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::DisputeDistribution(
+				DisputeDistributionMessage::DisputeSendingReceiver(_)
+			)
+		);
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::StatementDistribution(
@@ -1153,6 +1183,12 @@ fn send_messages_to_peers() {
 		network_handle.connect_peer(peer.clone(), PeerSet::Validation, ObservedRole::Full).await;
 		network_handle.connect_peer(peer.clone(), PeerSet::Collation, ObservedRole::Full).await;
 
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::DisputeDistribution(
+				DisputeDistributionMessage::DisputeSendingReceiver(_)
+			)
+		);
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::StatementDistribution(
@@ -1279,7 +1315,8 @@ fn spread_event_to_subsystems_is_up_to_date() {
 			AllMessages::ApprovalDistribution(_) => { cnt += 1; }
 			AllMessages::GossipSupport(_) => unreachable!("Not interested in network events"),
 			AllMessages::DisputeCoordinator(_) => unreachable!("Not interested in network events"),
-			AllMessages::DisputeParticipation(_) => unreachable!("Not interetsed in network events"),
+			AllMessages::DisputeParticipation(_) => unreachable!("Not interested in network events"),
+			AllMessages::DisputeDistribution(_) => unreachable!("Not interested in network events"),
 			AllMessages::ChainSelection(_) => unreachable!("Not interested in network events"),
 			// Add variants here as needed, `{ cnt += 1; }` for those that need to be
 			// notified, `unreachable!()` for those that should not.
@@ -1325,6 +1362,12 @@ fn our_view_updates_decreasing_order_and_limited_to_max() {
 			0,
 		);
 
+		assert_matches!(
+			virtual_overseer.recv().await,
+			AllMessages::DisputeDistribution(
+				DisputeDistributionMessage::DisputeSendingReceiver(_)
+			)
+		);
 		assert_matches!(
 			virtual_overseer.recv().await,
 			AllMessages::StatementDistribution(