refactor twitter to not be a mixin

fixes: CNVS-12118

test-plan:
*twitter integration should work

Change-Id: I44a9011eb451aaa8eb196264bb4b65d1635da083
Reviewed-on: https://gerrit.instructure.com/33065
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Reviewed-by: Mike Nomitch <mnomitch@instructure.com>
Reviewed-by: Liz Abinante <labinante@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>