client/authority-discovery: Allow to be run by sentry node (#5568)

* client/authority-discovery: Allow to be run by sentry node

When run as a sentry node, the authority discovery module does not
publish any addresses to the dht, but still discovers validators and
sentry nodes of validators.

* client/authority-discovery/src/lib: Wrap lines at 100 characters

* client/authority-discovery: Remove TODO and unused import

* client/authority-discovery: Pass role to new unit tests

* client/authority-discovery: Apply suggestions

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

* bin/node/cli/src/service: Use expressions instead of statements

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

substrate/client/authority-discovery/src/tests.rs

@@ -216,8 +216,8 @@ fn new_registers_metrics() {
 		test_api,
 		network.clone(),
 		vec![],
-		key_store,
 		dht_event_rx.boxed(),
+		Role::Authority(key_store),
 		Some(registry.clone()),
 	);
 
@@ -241,8 +241,8 @@ fn publish_ext_addresses_puts_record_on_dht() {
 		test_api,
 		network.clone(),
 		vec![],
-		key_store,
 		dht_event_rx.boxed(),
+		Role::Authority(key_store),
 		None,
 	);
 
@@ -272,8 +272,8 @@ fn request_addresses_of_others_triggers_dht_get_query() {
 		test_api,
 		network.clone(),
 		vec![],
-		key_store,
 		dht_event_rx.boxed(),
+		Role::Authority(key_store),
 		None,
 	);
 
@@ -301,8 +301,8 @@ fn handle_dht_events_with_value_found_should_call_set_priority_group() {
 		test_api,
 		network.clone(),
 		vec![],
-		key_store,
 		dht_event_rx.boxed(),
+		Role::Authority(key_store),
 		None,
 	);
 
@@ -366,8 +366,8 @@ fn terminate_when_event_stream_terminates() {
 		test_api,
 		network.clone(),
 		vec![],
-		key_store,
 		dht_event_rx.boxed(),
+		Role::Authority(key_store),
 		None,
 	);
 
@@ -407,8 +407,8 @@ fn dont_stop_polling_when_error_is_returned() {
 		test_api,
 		network.clone(),
 		vec![],
-		key_store,
 		dht_event_rx.boxed(),
+		Role::Authority(key_store),
 		None,
 	);