Save a questionnaire with its sections and questions

The builder's save. sections and questions are the questionnaire's complete desired content, not a patch: rows present are created or updated, rows absent are deleted along with their answers and comments. name, description and dueDate are always written; status is not settable here and keeps its stored value. The questionnaire must belong to the calling company — another company's is indistinguishable from a missing one and answers 404 — and a Retraced-owned questionnaire may only be saved by a Retraced admin. Once answer requests exist, an existing question's title, type, mandatory flag and options are frozen; adding a new question instead reopens every request so it can be answered. Moving the due date re-dates the still-open requests and notifies their answering companies. Answers the saved questionnaire in the same shape as the builder read.