Retrieves a quiz submission by ID, including its stored evaluation results.
Callers with site-wide read access can retrieve submissions from other submitters
on the same site. Site members with own-only access receive NOT_FOUND when
requesting another member's submission.
Read the result from quizSubmission. Changing quiz settings does not recalculate
the stored grade or passing-grade threshold.
This method doesn't return any custom errors, but may return standard errors. Learn more about standard Wix errors.