Change text field in quizzes to better conform to documentation.

Closes CNVS-11570

Test Plan:
  - create or edit a quiz
  - switch editors by clicking on "HTML Editor"
  - Confirm that the editor switch text now reads 'Rich Text Editor'.
  Extra WYSIWYG locations:
  - Confirm that assignments, syllabus content, calendar events, eportfolios, and wiki rich text editors are also edited
  - confirm that locales are updated

Change-Id: If110012fea46090dc2283bfba1170e82034e7ff5
Reviewed-on: https://gerrit.instructure.com/38729
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Josh Simpson <jsimpson@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Ryan Taylor <rtaylor@instructure.com>