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

FictionArchive.Service.NovelService/appsettings.json

@@ -12,5 +12,9 @@
   "ConnectionStrings": {
     "DefaultConnection": "Host=localhost;Database=FictionArchive_NovelService;Username=postgres;password=postgres"
   },
+  "RabbitMQ": {
+    "ConnectionString": "amqp://localhost",
+    "ClientIdentifier": "NovelService"
+  },
   "AllowedHosts": "*"
 }