Add contract type check to envelope validation

ValidateEnvelopeForSending now skips element checks if the envelope does not require a signature (i.e., contract type is not ReadAndSign), preventing unnecessary validation for such envelopes.

EnvelopeGenerator.Form/Controllers/EnvelopeEditorController.vb

@@ -50,6 +50,11 @@ Public Class EnvelopeEditorController
     Public Function ValidateEnvelopeForSending(pErrors As List(Of String)) As List(Of String)
         Dim oEnvelopeErrors = pErrors
 
+        Dim requiresSignature = (Envelope.ContractType = ContractType.ReadAndSign)
+        If requiresSignature = False Then
+            Return oEnvelopeErrors
+        End If
+
         If ElementModel.ElementsExist(Envelope.Id) = False Then
             oEnvelopeErrors.Add(Resources.Envelope.Missing_Elements)
         End If