Refactor enum usage in codebase

Updated references from `Constants` to direct usage of `EnvelopeStatus` and `EmailTemplateType` enums. This change enhances code readability and reduces dependency on the `Constants` class.

Modified properties and parameters across command classes, DTOs, repositories, and services to use the enums directly. Updated `ModifyDocStatusCommandBase`, `EnvelopeHistoryDto`, and `ResetEmailTemplateCommand` for improved clarity.

Consistent updates across multiple files indicate a systematic refactoring aimed at streamlining the codebase and improving maintainability. Comments and documentation have also been revised to reflect these changes.

EnvelopeGenerator.Application/EnvelopeReceivers/Queries/ReceiverAlreadySignedQuery.cs

@@ -72,7 +72,7 @@ public class ReceiverAlreadySignedQueryHandler : IRequestHandler<ReceiverAlready
         return await _repo.Read()
             .Where(er => er.Envelope.Uuid == request.Envelope.Uuid)
             .Where(er => er.Receiver.Signature == request.Receiver.Signature)
-            .Where(er => er.Envelope.History.Any(hist => hist.Status == Constants.EnvelopeStatus.DocumentSigned))
+            .Where(er => er.Envelope.History.Any(hist => hist.Status == EnvelopeStatus.DocumentSigned))
             .AnyAsync(cancel);
     }
 }