Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Core.Domain/Models/Folders/SystemFolderConfiguration.cs

@@ -0,0 +1,10 @@
+using Wino.Core.Domain.Entities.Mail;
+
+namespace Wino.Core.Domain.Models.Folders
+{
+    public record SystemFolderConfiguration(MailItemFolder SentFolder,
+                                            MailItemFolder DraftFolder,
+                                            MailItemFolder ArchiveFolder,
+                                            MailItemFolder TrashFolder,
+                                            MailItemFolder JunkFolder);
+}