make account reports a gem

fixes CNVS-14266

test plan
 - all account reports should still work

Change-Id: Ibc378d76571569760e733bd1b8ad87e299a7bff8
Reviewed-on: https://gerrit.instructure.com/41419
Product-Review: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>
Tested-by: Rob Orton <rob@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>