whitelist allowable data that is being included in quiz questions api for students

fixes CNVS-12231

test plan:
- as a teacher
  - create a quiz with all of the question types

- as a student
  - take the quiz

  - inspect element on the quiz questions
  - find the <div id="question_<number>etc...> or <div class="display_question
    question ...." id=" question<number>
  - expand the <div style="display: none;"> five entries below that & you'll
    see the link to where the quiz question json can be viewed
  - open the link
  - there should be no sensitive information revealed in the question json
  - this includes any answer info or comments by the teacher, etc

Change-Id: I1441b16256040274abae2ae96c9124b825946658
Reviewed-on: https://gerrit.instructure.com/32934
Reviewed-by: Josh Simpson <jsimpson@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>