Fix field type validation – propagate result of validation (#2914)

Small fix to field type validation. I forgot to propagate result of
field validation upper to the work item validation, so even if some
fields were not valid, the whole work item type claimed it is valid.

Author: MrHinsh

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsWorkItemTypeValidatorTool.cs

@@ -112,7 +112,7 @@ private bool ValidateWorkItemTypeFields(WorkItemType sourceWit, WorkItemType tar
                     }
                     else
                     {
-                        ValidateField(sourceField, targetFields[targetFieldName], targetWit.Name);
+                        result &= ValidateField(sourceField, targetFields[targetFieldName], targetWit.Name);
                     }
                 }
                 else
@@ -135,7 +135,7 @@ private bool ValidateWorkItemTypeFields(WorkItemType sourceWit, WorkItemType tar
             return result;
         }
 
-        private void ValidateField(FieldDefinition sourceField, FieldDefinition targetField, string targetWitName)
+        private bool ValidateField(FieldDefinition sourceField, FieldDefinition targetField, string targetWitName)
         {
             // If target field is in 'FixedTargetFields' list, it means, that user resolved this filed somehow.
             // For example by value mapping. So any discrepancies found will be logged just as information.
@@ -156,6 +156,7 @@ private void ValidateField(FieldDefinition sourceField, FieldDefinition targetFi
                     + $" because it is listed in '{nameof(Options.FixedTargetFields)}'.",
                     targetField.ReferenceName, targetWitName, sourceField.ReferenceName);
             }
+            return (logLevel == LogLevel.Information) || isValid;
         }
 
         private bool ValidateFieldType(FieldDefinition sourceField, FieldDefinition targetField, LogLevel logLevel)