[FA-4] Adds an event bus infrastructure, a RabbitMQ implementation and rewires existing mutations on NovelService to utilize it.

FictionArchive.Service.NovelService/Models/IntegrationEvents/NovelUpdateRequestedEvent.cs

@@ -0,0 +1,8 @@
+using FictionArchive.Service.Shared.Services.EventBus;
+
+namespace FictionArchive.Service.NovelService.Models.IntegrationEvents;
+
+public class NovelUpdateRequestedEvent : IntegrationEvent
+{
+    public string NovelUrl { get; set; }
+}