Add NoopEventPublisher, which will be used as default impl.

Introduces a NoopEventPublisher that implements the
EventPublisher trait, but performs no actions when publishing events.
It will serve as a convenient default implementation for scenarios
where no real event publishing mechanism is required, reducing the
burden on developers to provide an explicit publisher in all cases.

Author: G8XSU

ldk-server/src/io/events/event_publisher.rs

@@ -40,3 +40,16 @@ pub trait EventPublisher {
 	/// [`LdkServerErrorCode::InternalServerError`]: crate::api::error::LdkServerErrorCode
 	async fn publish(&self, event: EventEnvelope) -> Result<(), LdkServerError>;
 }
+
+pub(crate) struct NoopEventPublisher;
+
+#[async_trait]
+impl EventPublisher for NoopEventPublisher {
+	/// Publishes an event to a no-op sink, effectively discarding it.
+	///
+	/// This implementation does nothing and always returns `Ok(())`, serving as a
+	/// default when no messaging system is configured.
+	async fn publish(&self, _event: EventEnvelope) -> Result<(), LdkServerError> {
+		Ok(())
+	}
+}