adjust formatting for module locked message for students in ember quizzes

fixes CNVS-13223

test plan:
  - enable fabulous quizzes
  - as a teacher
    - create two quizzes
    - create two modules
    - add one quiz to the first module, and the other to the 2nd module
    - edit the 2nd module to have the first module as a prerequisite
  - as a student
    - visit the quiz in the module that hasn't met the prerequisite yet
    - you should get a nicely formatted message telling you why you can't
      take the quiz yet
    - complete the first module
    - once the 2nd module is unlocked you should be able to take the quiz
      again

Change-Id: I000c0b7d91867d950a3557c6d877cf61cfa5b589
Reviewed-on: https://gerrit.instructure.com/35559
Reviewed-by: Jason Madsen <jmadsen@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>