Handle "*" in NationalCode assignment gracefully

Updated the `NationalCode` assignment in the `CreateInstitutionContractLegalPartyRequest` object to replace `"*"` with an empty string (`string.Empty`). This ensures compliance with business rules where `"*"` is not considered a valid value for `NationalCode`. Retains the original value otherwise.

CompanyManagment.EFCore/Repository/InstitutionContractRepository.cs

@@ -1999,7 +1999,7 @@ public class InstitutionContractRepository : RepositoryBase<long, InstitutionCon
         {
             legalPartyRequest = new CreateInstitutionContractLegalPartyRequest()
             {
-                NationalCode = contractingParty.Nationalcode,
+                NationalCode = contractingParty.Nationalcode=="*"?string.Empty:contractingParty.Nationalcode,
                 BirthDateFa = contractingParty.DateOfBirth.ToFarsi(),
                 PhoneNumber = contractingParty.Phone,
                 FatherName = contractingParty.FatherName,