feat: merge OpenPGP certificates and distribute relays in them

We put all relay addresses as a notation subpacket
in the direct key signature to distribute the relay addresses.

src/transport.rs

@@ -669,6 +669,9 @@ pub(crate) async fn save_transport(
 pub(crate) async fn send_sync_transports(context: &Context) -> Result<()> {
     info!(context, "Sending transport synchronization message.");
 
+    // Regenerate public key to include all transports.
+    context.self_public_key.lock().await.take();
+
     // Synchronize all transport configurations.
     //
     // Transport with ID 1 is never synchronized
@@ -761,6 +764,7 @@ pub(crate) async fn sync_transports(
         .await?;
 
     if modified {
+        context.self_public_key.lock().await.take();
         tokio::task::spawn(restart_io_if_running_boxed(context.clone()));
         context.emit_event(EventType::TransportsModified);
     }