CQS: accessible answer bars chart

Closes CNVS-15303

Enhancements:

  - chart is ignored by SR
  - a table is now provided for SR instead that reads the response
    counts in a in a friendly manner:
    * each answer text is prepended with the answer position
    * correct answers are read as such
    * the answer text itself acts like the row's header, so you hear a
       full sentence describing both the answer and its response count
    * hearing-friendly response counts

Here's an example of what you'll hear for a table with the following
data:

[ A               | 50 ]
[ B               | 0  ]
[ Something else  | 5 ]
[ No answer       | 3 ]

"Answer one: A. This is a correct answer. Fifty responses."
"Answer two: B. No response."
"Answer three: Something else. Five responses."
"Answer four: No answer. Three responses."

TEST PLAN
---- ----

  - go to CQS
  - using SR, visit question boxes that have the Answer Distribution bar
    chart
    + verify you do not gain focus to the chart, it should be totally
      ignored by the SR
    + verify you hear the answers laid out as described above (I've had
      to use the table mode in VoiceOver for this effect)

Change-Id: Iad32a3b5ed652ab531b9b1bc98a3a4dcf91d0dfd
Reviewed-on: https://gerrit.instructure.com/41331
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ryan Taylor <rtaylor@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>