namespace all of quiz into quizzes module

This commit namespaces the rest of quiz related code into a Quizzes
namespace: controllers, views, models, and classes that previously lived
under lib/ that are Quiz-related.

Test plan:

Full regression test on all quiz related items

refs CNVS-10457

Change-Id: If54b61213945056539e03271a936d233abb66188
Reviewed-on: https://gerrit.instructure.com/29351
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Myller de Araujo <myller@instructure.com>
Reviewed-by: Jason Madsen <jmadsen@instructure.com>
Product-Review: Josh Simpson <jsimpson@instructure.com>