[datafeed] Add a raise_on_error parameter to DataFeedSource.extid2entity And pass the option from various `process_` methods in existing parsers. This makes debugging in tests easier. Closes #4601191.

if not rql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',
           ask_confirm=False):
    rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',
        ask_confirm=False)