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

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

@@ -0,0 +1,17 @@
+using FictionArchive.Common.Enums;
+using FictionArchive.Service.Shared.Services.EventBus;
+
+namespace FictionArchive.Service.NovelService.Models.IntegrationEvents;
+
+public class TranslationRequestCompletedEvent : IntegrationEvent
+{
+    /// <summary>
+    /// Maps this event back to a triggering request.
+    /// </summary>
+    public Guid? TranslationRequestId { get; set; }
+    
+    /// <summary>
+    /// The resulting text.
+    /// </summary>
+    public string? TranslatedText { get; set; }
+}