Add mandatory marker on questions #3741

For the internal surveys, some questions are required.
This commit defines some questions with the :is_mandatory attribute.

Also only phase two consents should create the associated
participant consent sample records.
Required consent attributes #2106

Pulling code from Registar implement mandatory fields
in Surveyor. That is if a question is marked as mandatory
redirect the user to that section of the survey if the user
attempts to "finish" the survey but has yet to answer all
mandatory questions.
Updated documentation #2106
Merge pull request #156 from NUBIC/2106-require_withdrawal_date

2106 require withdrawal date