Dispute Coordinator Subsystem (#3150)

* skeleton for dispute-coordinator

* add coordinator and participation message types

* begin dispute-coordinator DB

* functions for loading

* implement strongly-typed DB transaction

* add some tests for DB transaction

* core logic for pruning

* guide: update candidate-votes key for coordinator

* update candidate-votes key

* use big-endian encoding for session, and implement upper bound generator

* finish implementing pruning

* add a test for note_current_session

* define state of the subsystem itself

* barebones subsystem definition

* control flow

* more control flow

* implement session-updating logic

* trace

* control flow for message handling

* Update node/core/dispute-coordinator/src/lib.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* Update node/subsystem/src/messages.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* some more control flow

* guide: remove overlay

* more control flow

* implement some DB getters

* make progress on importing statements

* add SignedDisputeStatement struct

* move ApprovalVote to shared primitives

* add a signing-payload API to explicit dispute statements

* add signing-payload to CompactStatement

* add relay-parent hash to seconded/valid dispute variatns

* correct import

* type-safe wrapper around dispute statements

* use checked dispute statement in message type

* extract rolling session window cache to subsystem-util

* extract session window tests

* approval-voting: use rolling session info cache

* reduce dispute window to match runtime in practice

* add byzantine_threshold and supermajority_threshold utilities to primitives

* integrate rolling session window

* Add PartialOrd to CandidateHash

* add Ord to CandidateHash

* implement active dispute update

* add dispute messages to AllMessages

* add dispute stubs to overseer

* inform dispute participation to participate

* implement issue_local_statement

* implement `determine_undisputed_chain`

* fix warnings

* test harness for dispute coordinator tests

* add more helpers to test harness

* add some more helpers

* some tests for dispute coordinator

* ignore wrong validator indices

* test finality voting rule constraint

* add more tests

* add variants to network bridge

* fix test compilation

* remove most dispute coordinator functionality

as of #3222 we can do most of the work within the approval voting subsystem

* Revert "remove most dispute coordinator functionality"

This reverts commit 9cd615e8eb6ca0b382cbaff525d813e753d6004e.

* Use thiserror

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* Update node/core/dispute-coordinator/src/lib.rs

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* extract tests to separate module

* address nit

* adjust run_iteration API

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

polkadot/Cargo.lock

@@ -6091,6 +6091,30 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "polkadot-node-core-dispute-coordinator"
+version = "0.1.0"
+dependencies = [
+ "assert_matches",
+ "bitvec",
+ "derive_more",
+ "futures 0.3.15",
+ "kvdb",
+ "kvdb-memorydb",
+ "parity-scale-codec",
+ "polkadot-node-primitives",
+ "polkadot-node-subsystem",
+ "polkadot-node-subsystem-test-helpers",
+ "polkadot-node-subsystem-util",
+ "polkadot-primitives",
+ "sc-keystore",
+ "sp-core",
+ "sp-keyring",
+ "sp-keystore",
+ "thiserror",
+ "tracing",
+]
+
 [[package]]
 name = "polkadot-node-core-parachains-inherent"
 version = "0.1.0"
@@ -6221,6 +6245,7 @@ dependencies = [
  "sp-consensus-babe",
  "sp-consensus-vrf",
  "sp-core",
+ "sp-keystore",
  "sp-maybe-compressed-blob",
  "sp-runtime",
  "thiserror",