pvf-precheck: PVF pre-checker subsystem (#4643)

This commit implements the last major piece of #3211: the subsystem that
tracks PVFs that require voting, issues pre-check requests to
candidate-validation and makes sure that the votes are submitted to the
chain.

polkadot/node/service/src/lib.rs

@@ -732,6 +732,8 @@ where
 		chain_spec.is_versi() ||
 		chain_spec.is_wococo();
 
+	let pvf_checker_enabled = !is_collator.is_collator() && chain_spec.is_versi();
+
 	let select_chain = if requires_overseer_for_chain_sel {
 		let metrics =
 			polkadot_node_subsystem_util::metrics::Metrics::register(prometheus_registry.as_ref())?;
@@ -979,6 +981,7 @@ where
 					chain_selection_config,
 					dispute_coordinator_config,
 					disputes_enabled,
+					pvf_checker_enabled,
 				},
 			)
 			.map_err(|e| {

polkadot/node/service/src/overseer.rs

@@ -61,6 +61,7 @@ pub use polkadot_node_core_chain_api::ChainApiSubsystem;
 pub use polkadot_node_core_chain_selection::ChainSelectionSubsystem;
 pub use polkadot_node_core_dispute_coordinator::DisputeCoordinatorSubsystem;
 pub use polkadot_node_core_provisioner::ProvisionerSubsystem;
+pub use polkadot_node_core_pvf_checker::PvfCheckerSubsystem;
 pub use polkadot_node_core_runtime_api::RuntimeApiSubsystem;
 pub use polkadot_statement_distribution::StatementDistributionSubsystem;
 
@@ -109,6 +110,8 @@ where
 	pub dispute_coordinator_config: DisputeCoordinatorConfig,
 	/// Enable to disputes.
 	pub disputes_enabled: bool,
+	/// Enable PVF pre-checking
+	pub pvf_checker_enabled: bool,
 }
 
 /// Obtain a prepared `OverseerBuilder`, that is initialized
@@ -136,12 +139,14 @@ pub fn prepared_overseer_builder<'a, Spawner, RuntimeClient>(
 		chain_selection_config,
 		dispute_coordinator_config,
 		disputes_enabled,
+		pvf_checker_enabled,
 	}: OverseerGenArgs<'a, Spawner, RuntimeClient>,
 ) -> Result<
 	OverseerBuilder<
 		Spawner,
 		Arc<RuntimeClient>,
 		CandidateValidationSubsystem,
+		PvfCheckerSubsystem,
 		CandidateBackingSubsystem<Spawner>,
 		StatementDistributionSubsystem,
 		AvailabilityDistributionSubsystem,
@@ -208,6 +213,7 @@ where
 			Metrics::register(registry)?, // candidate-validation metrics
 			Metrics::register(registry)?, // validation host metrics
 		))
+		.pvf_checker(PvfCheckerSubsystem::new(pvf_checker_enabled, keystore.clone()))
 		.chain_api(ChainApiSubsystem::new(runtime_client.clone(), Metrics::register(registry)?))
 		.collation_generation(CollationGenerationSubsystem::new(Metrics::register(registry)?))
 		.collator_protocol({