add extend time modal link and dialog for ember quizzes moderate

fixes CNVS-12448

test plan:
- as a teacher
  - enable fabulous quizzes
  - enroll a few students in the course

  - create a quiz with a time limit
  - publish the quiz
  - visit the quiz moderate page

- in a different browser / session as a student
  - start the quiz as a student
  - don't submit the quiz yet!

- as a teacher
  - refresh the moderate page
  - you should be shown a clock icon for the students with currently running
    quizzes.
  - you can now click on this icon!
  - this will bring up a modal dialog to extend time for the current attempt
  - try out extending the quiz by a few minutes from now
  - try out extending the quiz by a few minutes from the end date

- also try these out with multiple students taking the quiz at once.
- changing the options in the modal should persist until you choose a different
  student, at which point it will reset the form in the dialog

Change-Id: I0adf1ed2133b6adaf8501b5131bd70365b06c249
Reviewed-on: https://gerrit.instructure.com/35343
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ahmad Amireh <ahmad@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>