refactor(publisher): introduce MessagingServicePublisherConfiguration builder

Replace Action<RabbitMqConfiguration> parameter on AddMessagingServicePublisher()
with a builder to keep the publisher API consistent with the infrastructure layer.

- Add MessagingServicePublisherConfiguration exposing
  AddRabbitMqConnectionFactory() with IConfiguration and Action<T> overloads
- Callers that need RabbitMQ must now call cfg.AddRabbitMqConnectionFactory(...)
  inside the configure delegate instead of configuring RabbitMQ directly

src/infrastructure/DigitalData.MessagingService.Publisher/DependencyInjection.cs

@@ -1,15 +1,17 @@
 using DigitalData.MessagingService.Application.Common.Interfaces;
 using DigitalData.MessagingService.RabbitMQ;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace DigitalData.MessagingService.Publisher;
 
 public static class DependencyInjection
 {
-    public static IServiceCollection AddMessagingServicePublisher(this IServiceCollection services, Action<RabbitMqConfiguration>? configure = null)
+    public static IServiceCollection AddMessagingServicePublisher(this IServiceCollection services, Action<MessagingServicePublisherConfiguration>? configure = null)
     {
-        if(configure is not null)
-            services.AddRabbitMqConnectionFactory(configure);
+        var configuration = new MessagingServicePublisherConfiguration(services);
+
+        configure?.Invoke(configuration);
 
         // --- Email Queue (RabbitMQ) ---
         services.AddSingleton<ISendingEmailPublisher, SendingEmailPublisher>();

src/infrastructure/DigitalData.MessagingService.Publisher/MessagingServicePublisherConfiguration.cs

@@ -0,0 +1,27 @@
+using DigitalData.MessagingService.RabbitMQ;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace DigitalData.MessagingService.Publisher;
+
+public class MessagingServicePublisherConfiguration
+{
+    internal IServiceCollection Services { get; }
+
+    internal MessagingServicePublisherConfiguration(IServiceCollection services)
+    {
+        Services = services;
+    }
+
+    public MessagingServicePublisherConfiguration AddRabbitMqConnectionFactory(Action<RabbitMqConfiguration> configure)
+    {
+        Services.AddRabbitMqConnectionFactory(configure);
+        return this;
+    }
+
+    public MessagingServicePublisherConfiguration AddRabbitMqConnectionFactory(IConfiguration configuration, string sectionName = RabbitMqConfiguration.SectionName)
+    {
+        Services.AddRabbitMqConnectionFactory(configuration, sectionName);
+        return this;
+    }
+}