Add a check to verify if a simple type has been changed to a structured type. Please consider expression columns too

Use case to cover:

• data type customString in a DMN defined as alias of String
• test scenario created (customString will generate a single column because it is a simple type)
• data type changed of customString to structure
• validation error in test scenario

We will need to check also validation of test scenario expression columns (= column where user map the whole object)

EDIT:
String to List<String> should be already covered by current validation implementation