Maintain and print source mapping with schema validation warnings

[ubmarco]

Currently the schema validation warnings look like this:

  ERROR: Need 'IMPL_1' has schema violations:
    Severity:       violation
    Field:          start_date
    Need path:      IMPL_1
    Schema path:    options > schema > properties > start_date > format
    Schema message: "not-a-date" is not a "date" [sn_schema_violation.option_fail]

The internal data structure should store a source mapped information and emit it with each warning.
This also needs to be part of the schema_violations.json file.