CQS: Essay, File Upload, and Formula

This is the last part of Ember to CQS port. Adds question statistics
boxes for these question types.

Closes CNVS-15260

TEST PLAN
---- ----

  - create a quiz with those question types
  - take it by a number of students
  - visit the stats cqs page
  - verify the question stats render
  - verify the score distribution chart is functional
    + pls note that none of the scores will show until the teacher
      actually grades the responses
  - verify the correct answer donut chart is functional
  - verify the "Attempts: X out of Y" is functional:
    + when you write nothing in essay or formula, you don't count as an
      attempt
    + when you don't upload a file, you don't count as an attempt
  - verify the essay stats shows a link "View in SpeedGrader" that takes
    you to speedgrader
  - verify the file upload box shows a link "Download All Files" that
    opens a new tab, generates the zip file, and downloads it

Change-Id: Ibd72b32a21a508a78b1eb14a2b438f6fe4398451
Reviewed-on: https://gerrit.instructure.com/40544
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Ahmad Amireh <ahmad@instructure.com>