wrap core_ext module in Canvas for zeitwerk
wrap core_ext module in Canvas for zeitwerk

refs https://instructure.atlassian.net/browse/FOO-2476
flag=none

TEST PLAN:
  1) specs pass

Change-Id: Iaa6a7150eb1eb0bd2bc778a5ef2df540eefde500
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/275962
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
QA-Review: Ethan Vizitei <73eeb0b2f65d05a906adf3b21ee1f9f5a2aa3c1c@instructure.com>
Product-Review: Ethan Vizitei <73eeb0b2f65d05a906adf3b21ee1f9f5a2aa3c1c@instructure.com>
Reviewed-by: Jacob Burroughs <8ecea6e385af5cf9f53123f5ca17fb5fd6a6d4b2@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms