client: Introduce --sentry-nodes flag (#4285)

* client/authority-discovery: Add smoke tests for intervall_at

* client/authority-discovery: Fix interval_at to fire on start

* .maintain/sentry-node: Update docker compose file

* client: Introduce --sentry-nodes flag

Enable operators to specify the public addresses of sentry nodes infront
of a validator node so that the validator node can announce the sentry
node addresses instead of its own public addresses on the DHT via the
authority discovery module.

* client/authority-discovery: Break lines at 100 characters

Limit line length to 100 instead of 120 characters.

substrate/bin/node/cli/src/service.rs

@@ -125,12 +125,14 @@ macro_rules! new_full {
 			is_authority,
 			force_authoring,
 			name,
-			disable_grandpa
+			disable_grandpa,
+			sentry_nodes,
 		) = (
 			$config.roles.is_authority(),
 			$config.force_authoring,
 			$config.name.clone(),
-			$config.disable_grandpa
+			$config.disable_grandpa,
+			$config.network.sentry_nodes.clone(),
 		);
 
 		// sentry nodes announce themselves as authorities to the network
@@ -194,6 +196,7 @@ macro_rules! new_full {
 			let authority_discovery = authority_discovery::AuthorityDiscovery::new(
 				service.client(),
 				service.network(),
+				sentry_nodes,
 				service.keystore(),
 				future03_dht_event_rx,
 			);