change 'show results' to 'show responses' in quiz overview

fixes CNVS-13459
This commit changes the wording from 'Show Results' to 'Show Responses'
in the Quiz overview page, to prevent confusion.

Test plan
- View the ember quiz overview page
- The 'Show Results' setting should now read as 'Show Responses'

Change-Id: Ife3729f5cbca7bdccd7ab2f9bfd4b2c77b2d8687
Reviewed-on: https://gerrit.instructure.com/35970
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jason Madsen <jmadsen@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>
Product-Review: Josh Simpson <jsimpson@instructure.com>