Refactored the `Email` and `OutgoingEmailEvent` classes to replace the `Recipient` property with a `Recipients` collection, enabling support for multiple recipients. Updated all related test cases, including `EmailSenderTests`, `EmailSenderUrlOverloadTests`, and `OutgoingEmailPublisherTests`, to reflect this change.
Moved the `EmailAccountDto` class and its references from the `DigitalData.MessagingService.Application.Common.Dtos` namespace to the `DigitalData.MessagingService.Publisher.Abstraction` namespace for better code organization. Updated `using` directives across affected files.
Removed unused `using` directives and updated the `Email` class's `ToEvent` method to map the new `Recipients` property. Adjusted test assertions to validate collections instead of single recipient strings.
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.
