Replace AsyncInitWorker with ConsumerInitWorker

Replaced the `AsyncInitWorker` background service with the new `ConsumerInitWorker`, which introduces enhanced error handling, logging, and configurability for RabbitMQ consumer initialization.

Updated `MessagingServiceDbContext` to remove the `UseCollation` configuration for the `Username` property in the `EmailAccount` entity, ensuring compatibility with the InMemory database.

Added the `ContinueOnInitFailure` property to `RabbitMqConfiguration` to allow the application to continue running if RabbitMQ consumer initialization fails.

Cleaned up unused `using` directives in `DependencyInjection.cs` and removed the obsolete `AsyncInitWorker` class.

src/infrastructure/DigitalData.MessagingService.RabbitMQ/RabbitMqConfiguration.cs

@@ -81,5 +81,7 @@ namespace DigitalData.MessagingService.RabbitMQ
         /// Maps directly to RabbitMQ prefetchCount. Recommended: 3–5.
         /// </summary>
         public ushort ConsumerConcurrency { get; set; } = 5;
+
+        public bool ContinueOnInitFailure { get; set; } = false;
     }
 }