Add EmailOut components: entity, DTO, repository, and services

- Introduced EmailOut and EmailOutDto for data management.
- Added EmailOutRepository and service interfaces based on CRUD patterns.

EnvelopeGenerator.Application/Contracts/IEmailOutService.cs

@@ -0,0 +1,11 @@
+using DigitalData.Core.Contracts.Application;
+using EnvelopeGenerator.Application.DTOs;
+using EnvelopeGenerator.Domain.Entities;
+using EnvelopeGenerator.Infrastructure.Contracts;
+
+namespace EnvelopeGenerator.Application.Contracts
+{
+    public interface IEmailOutService : IBasicCRUDService<IEmailOutRepository, EmailOutDto, EmailOut, int>
+    {
+    }
+}