outcome results api: filter by outcome

fixes CNVS-10041

test plan:
  * make an API call to the outcomes service
  * add an outcome_ids parameter to your URL
  * verify that only the outcomes you specified are returned
  * add an outcome_group_id parameter to your original URL
  * verify that only outcomes in the group you specified are returned
  * add both parameters
  * verify that an error message is returned

Change-Id: Id31361a5937b36eb66765d29cbce3f1ce24e0d0f
Reviewed-on: https://gerrit.instructure.com/28364
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>
Reviewed-by: Zach Pendleton <zachp@instructure.com>
Product-Review: Braden Anderson <banderson@instructure.com>