Feature for QuestionDeclaredInvalid events

[andreaskutka]

Problem
An unusual number of validation messages flagged during the interview (but not necessarily outstanding at time of submission) may be indicative or problems, e.g., an interviewer who is struggling with a particular questions, or Interviewers who may use validation checks to probe for legitimate answers, especially at the beginning of fieldwork, while questionnaires and valid responses are not yet known.

Solution
Count of QuestionDeclaredInvalid events in Paradata once SurveySolution functionality becomes available.