Course Quiz Extension:  A course level quiz extension API

ProServe wants an API endpoint for their LTI which allows for editing of all quizzes
contained in a course similar to that provided by the Quiz Extensions
API endpoint.  This provides the ability to edit all quizzes at the
course level with the same type of parameters.

Closes: CNVS-14950

Test Plan:
  - Access /api/v1/courses/:course_id/quiz_extensions with POST
  - Pass quiz extensions parameters
  - Confirm that all quizzes are edited with the appropriate parameters

Change-Id: Ifca1a4937ab356665627ef3f0aa829aeeaddedc7
Reviewed-on: https://gerrit.instructure.com/40331
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Ryan Taylor <rtaylor@instructure.com>