add hooks to Api to find objects from other root accounts

refs CNVS-1180

Change-Id: Ic3e023e1869eefb75efedec028fb54f6fc995918
Reviewed-on: https://gerrit.instructure.com/31948
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>