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

FictionArchive.Service.Shared/Services/EventBus/EventBusExtensions.cs

@@ -0,0 +1,12 @@
+using Microsoft.Extensions.DependencyInjection;
+
+namespace FictionArchive.Service.Shared.Services.EventBus;
+
+public static class EventBusExtensions
+{
+    public static EventBusBuilder<TEventBus> AddEventBus<TEventBus>(this IServiceCollection services)
+        where TEventBus : class, IEventBus
+    {
+        return new EventBusBuilder<TEventBus>(services);
+    }
+}