Fix quiz titles in user access reports

Since Quiz has been namespaced under Quizzes, the asset user access code
changed from 'quizzes:quiz_id' to 'quizzes/quiz_id' which is out of sync
with the asset codes for the rest of the resources.

Closes CNVS-11191

CR NOTES
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See config/initializers/active_record.rb:128#asset_string to get an idea
why Quiz#reflection_type_name was overridden. It seemed to me this is
the point that is queried by that and relevant methods.

TEST PLAN
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  - create a quiz, and view it as a student
  - go to the user access report and verify that the quiz entry displays
    its title instead of quizzes/quiz_%id

Change-Id: I0e6eb3cc1c9ad069ef86db1e106c672bfe402df6
Reviewed-on: https://gerrit.instructure.com/30216
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Josh Simpson <jsimpson@instructure.com>
QA-Review: Myller de Araujo <myller@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>