XmlValidation: schema validation should return a structured error report not a list of strings

[ppazos]

The issue with the list of strings is we can't provide much detail about the error but internally we are processing the exceptions that contain structured data that we can return in the error report.

For instance, returning the XML path or line number where the error happens would be useful, or even the specific element name.

Check what we are returning in the JSON schema validation.