#175: Change handling of expansion related errors

[mohit-s96]

closes #175

This fixes the main issue from #175 and also adds the new fields sourceModel and sourceModelField to the schema validation error report. Errors in expanded items will now be reported using these new fields so it's clear which field failed and for which model.

For eg. this is what an error in Property->ListAgent(Member type)->MemberEmail would look like:

{
    "description": "RESO Common Format Schema Validation Summary",
    "generatedOn": "2024-08-28T14:10:31.557Z",
    "version": "2.0",
    "totalErrors": 1,
    "totalWarnings": 0,
    "items": [
        {
            "resourceName": "Property",
            "fieldName": "ListAgent",
            "errors": [
                {
                    "message": "MUST be string or null but found integer",
                    "occurrences": [
                        {
                            "count": 1,
                            "fileName": "payload.json",
                            "sourceModel": "Member",
                            "sourceModelField": "MemberEmail"
                        }
                    ]
                }
            ],
            "warnings": []
        }
    ]
}