Generally more informative validator output for some messages (plus some)

• Generally repaired validation 'sources' ('source_trail') context recording to cover all applicable validation message cases (especially, edge 'qualifier' validation); tested with unit tests
• TRAPIGraphType class moved up the class/module hierarchy, alongside ValidatorReporter; strict_validation as Optional[bool] wrapped in the is_strict_validation() method which uses graph_type to decide on None default strictness (based on graph type)
• TRAPI and Biolink Model versions resolved now only reported in logger.info, not stderr
• only preset target_provenance in validator reporter constructors, not the various method signatures
• add 'categories' into edge context labels for reports (long lists of categories may be challenging here but ...)