Refactor Email to EmailContext across codebase

Replaced the `Email` record with the new `EmailContext` record to introduce additional context and functionality in email handling. Updated property definitions to distinguish between .NET Framework (`set`) and other frameworks (`init`).

Modified `SendingEmailEvent` to use `EmailContext` for the `Mail` property. Updated mappings in `EmailMappingProfile` to map `SendEmailCommand` to `EmailContext`. Adjusted `SendEmailCommandHandler` to use `EmailContext` when mapping requests.

Refactored `EmailSender` to use `EmailContext` in its `Send` method, including updates to method signatures and documentation. Updated all related test classes (`EmailSenderTests`, `EmailSenderUrlOverloadTests`, `SendingEmailPublisherTests`) to validate the behavior of `EmailContext`, ensuring consistency and thorough testing of the transition.

These changes ensure compatibility across frameworks and improve the maintainability of the email handling process.

src/core/DigitalData.MessagingService.Abstraction/EmailContext.cs

@@ -1,6 +1,6 @@
 namespace DigitalData.MessagingService.Abstraction;
 
-public record Email
+public record EmailContext
 {
 #if NETFRAMEWORK
     public EmailAccountDto Sender { get; set; } = null!;

src/core/DigitalData.MessagingService.Abstraction/SendingEmailEvent.cs

@@ -9,9 +9,9 @@ public record SendingEmailEvent
 #endif
 
 #if NETFRAMEWORK
-    public Email Mail { get; set; } = null!;
+    public EmailContext Mail { get; set; } = null!;
 #else
-    public required Email Mail { get; init; }
+    public required EmailContext Mail { get; init; }
 #endif
 
 #if NETFRAMEWORK

src/core/DigitalData.MessagingService.Application/Common/Mappings/EmailMappingProfile.cs

@@ -13,6 +13,6 @@ public class EmailMappingProfile : Profile
     {
         // SendEmailCommand -> Email
         // Sender is resolved via MediatR in the handler and set separately after mapping.
-        CreateMap<SendEmailCommand, Email>();
+        CreateMap<SendEmailCommand, EmailContext>();
     }
 }

src/core/DigitalData.MessagingService.Application/EmailSending/Commands/SendEmailCommand.cs

@@ -46,7 +46,7 @@ public class SendEmailCommandHandler(ISender Sender, ISendingEmailPublisher Publ
             ?? throw new NotFoundException(
                 $"No email account found for the given sender criteria (Id: {request.Sender.Id}, Username: {request.Sender.Username}).");
 
-        var email = Mapper.Map<Email>(request) with { Sender = senderAccount };
+        var email = Mapper.Map<EmailContext>(request) with { Sender = senderAccount };
 
         // Enqueue to RabbitMQ
         var sendingEmailEvent = new SendingEmailEvent()