Add RabbitMQ integration tests and URL parsing logic

Enhanced test coverage for RabbitMQ integration by adding:
- New package references for dependency injection, logging, and RabbitMQ.
- `EmailSenderCollection` and `EmailSenderFixture` for managing static client lifecycle in integration tests.
- Integration tests for `EmailSender` and `OutgoingEmailPublisher` to verify connection management, message publishing, and serialization.
- `EmailSenderUrlOverloadTests` to validate URL-based connection overload behavior.
- `RabbitMqTestConfig` for centralized RabbitMQ test configuration.
- Unit tests for URL parsing logic in `EmailSenderUrlParsingTests`.

These changes improve reliability, maintainability, and test coverage for the messaging service.

tests/DigitalData.MessagingService.Tests/RabbitMqTestConfig.cs

@@ -0,0 +1,39 @@
+using DigitalData.MessagingService.RabbitMQ;
+
+namespace DigitalData.MessagingService.Tests;
+
+/// <summary>
+/// Shared RabbitMQ connection settings used across integration tests.
+/// Reads from the real broker defined in appsettings.Secrets.json.
+/// </summary>
+internal static class RabbitMqTestConfig
+{
+    public const string HostName = "172.24.12.56";
+    public const int Port = 5672;
+    public const string UserName = "admin";
+    public const string Password = "fl!'D}4;pYBb\\VD&{6]]G*\\0Bq8fVIn0j?Sgm\\2A,6GS47g5Dj";
+    public const string VirtualHost = "/";
+
+    public const string QueueName = "emailprofiler.email.outbox";
+    public const string ExchangeName = "emailprofiler.emails";
+    public const string RoutingKey = "email.outbox";
+    public const string DlqQueueName = "emailprofiler.email.outbox.dlq";
+    public const string DlqExchangeName = "emailprofiler.emails.dlq";
+    public const string DlqRoutingKey = "email.outbox.dlq";
+
+    public static void Apply(RabbitMqConfiguration cfg)
+    {
+        cfg.HostName = HostName;
+        cfg.Port = Port;
+        cfg.UserName = UserName;
+        cfg.Password = Password;
+        cfg.VirtualHost = VirtualHost;
+        cfg.QueueName = QueueName;
+        cfg.ExchangeName = ExchangeName;
+        cfg.RoutingKey = RoutingKey;
+        cfg.DlqQueueName = DlqQueueName;
+        cfg.DlqExchangeName = DlqExchangeName;
+        cfg.DlqRoutingKey = DlqRoutingKey;
+    }
+}
+