refactor+feat: allow subsystems to send only declared messages, generate graphviz (#5314)

Closes #3774
Closes #3826

polkadot/node/overseer/src/dummy.rs

@@ -15,8 +15,8 @@
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
 use crate::{
-	prometheus::Registry, AllMessages, HeadSupportsParachains, InitializedOverseerBuilder,
-	MetricsTrait, Overseer, OverseerMetrics, OverseerSignal, OverseerSubsystemContext, SpawnNamed,
+	prometheus::Registry, HeadSupportsParachains, InitializedOverseerBuilder, MetricsTrait,
+	Overseer, OverseerMetrics, OverseerSignal, OverseerSubsystemContext, SpawnNamed,
 	KNOWN_LEAVES_CACHE_SIZE,
 };
 use lru::LruCache;
@@ -30,11 +30,7 @@ pub struct DummySubsystem;
 
 impl<Context> Subsystem<Context, SubsystemError> for DummySubsystem
 where
-	Context: SubsystemContext<
-		Signal = OverseerSignal,
-		Error = SubsystemError,
-		AllMessages = AllMessages,
-	>,
+	Context: SubsystemContext<Signal = OverseerSignal, Error = SubsystemError>,
 {
 	fn start(self, mut ctx: Context) -> SpawnedSubsystem<SubsystemError> {
 		let future = Box::pin(async move {