fix missing moderate link for practice quizzes

fixes CNVS-7865
The 'Moderate Quiz' link wasn't showing for practice quizzes because of
how JavaScript decides to display the right bar.  In quiz_show.js, it
checks to see if there are any <li> elements as descendants of
ul.page-action-list, and displays ul.page-action-list if there are.
The Moderate Quiz link wasn't wrapped in an <li> tag, and since there
were no other <li> elements rendered, ul.page-action-list wasn't displaying.
It would display after students had taken the test, since that would
render the Statistics link (which was properly wrapped in an <li>)

Test plan
- Create a practice quiz
- You should see the 'Moderate This Quiz' link in the right sidebar,
  regardless of whether or not students have taken the quiz yet.

Change-Id: I08f0cec724ada62a4e49c8218321149da9f5f83b
Reviewed-on: https://gerrit.instructure.com/32985
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Stanley Stuart <stanley@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Josh Simpson <jsimpson@instructure.com>