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/statement-distribution/src/tests.rs

@@ -18,6 +18,7 @@ use std::time::Duration;
 use std::sync::Arc;
 use std::iter::FromIterator as _;
 use parity_scale_codec::{Decode, Encode};
+use polkadot_node_subsystem_test_helpers::mock::make_ferdie_keystore;
 use super::*;
 use sp_keyring::Sr25519Keyring;
 use sp_application_crypto::{AppKey, sr25519::Pair, Pair as TraitPair};
@@ -1704,14 +1705,3 @@ fn make_session_info(validators: Vec<Pair>, groups: Vec<Vec<u32>>) -> SessionInf
 		needed_approvals: 0,
 	}
 }
-
-pub fn make_ferdie_keystore() -> SyncCryptoStorePtr {
-	let keystore: SyncCryptoStorePtr = Arc::new(LocalKeystore::in_memory());
-	SyncCryptoStore::sr25519_generate_new(
-		&*keystore,
-		ValidatorId::ID,
-		Some(&Sr25519Keyring::Ferdie.to_seed()),
-		)
-		.expect("Insert key into keystore");
-	keystore
-}