Introduced EnvelopeTypeId as a read-only property in EmailData, set during construction. Updated TemplateService.InitDictionary to use EnvelopeTypeId for determining signature type and message content, replacing the hardcoded [SIGNATURE_TYPE] value. Also added necessary imports for domain entities and constants.
Updated the `CertificateModel.vb` and `EmailData.vb` files to replace direct access to the `FullName` property with the `GetFullName()` method for retrieving creator, sender, and receiver names. This change enhances flexibility and maintains consistency across the codebase.
Additionally, added a new static `GetFullName` method in the `EGUserExtensions.cs` file to centralize the formatting of user names by concatenating the `Prename` and `Name` properties.
