allow AR::Base objects in Shard.*_id_for stubs
allow AR::Base objects in Shard.*_id_for stubs

test-plan:
 - specs pass

Change-Id: I6fd8e53fe9c22a00fdf74f6a9860b0adbda0018d
Reviewed-on: https://gerrit.instructure.com/22546
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Product-Review: Jacob Fugal <f862f167b85d41b225785c70d70808bc7337c1fe@instructure.com>
QA-Review: Jacob Fugal <f862f167b85d41b225785c70d70808bc7337c1fe@instructure.com>

landonwilkins/canvas-lms,merichar/canvas-lms,kyroskoh/canvas-lms,sfu/canvas-lms,SwinburneOnline/canvas-lms,antoniuslin/canvas-lms,ShreniiNepal/shrenii_lmp,jay3126/canvas-lms,wimemx/Canvas,va7map/canvas-lms,sdeleon28/canvas-lms,dgynn/canvas-lms,juoni/canvas-lms,matematikk-mooc/canvas-lms,gbleydon/canvas-lms,utkarshx/canvas-lms,Jyaasa/canvas-lms,AndranikMarkosyan/lms,utkarshx/canvas-lms,skmezanul/canvas-lms,shidao-fm/canvas-lms,HotChalk/canvas-lms,wrdsb/canvas-lms,kyroskoh/canvas-lms,venturehive/canvas-lms,Unow/canvas-lms,venturehive/canvas-lms,leftplusrightllc/canvas-lms,samuels410/greatlakes-lms,grahamb/canvas-lms,arrivu/qibla-ecampus,efrj/canvas-lms,dgynn/canvas-lms,arrivu/hoodemo,arrivu/jigsaw-lms,utkarshx/canvas-lms,merichar/canvas-lms,fronteerio/canvas-lms,grahamb/canvas-lms,samuels410/greatlakes-lms,ShreniiNepal/shrenii_lmp,tgroshon/canvas-lms,SwinburneOnline/canvas-lms,jay3126/canvas-lms,va7map/canvas-lms,eCNAP/CANVAS,wye0220/shindig-canvas,tgroshon/canvas-lms,kyroskoh/canvas-lms,loganrun/pincan,arrivu/qibla-ecampus,sdeleon28/canvas-lms,arrivu/jigsaw-lms,sfu/canvas-lms,Jyaasa/canvas-lms,merichar/canvas-lms,leftplusrightllc/canvas-lms,efrj/canvas-lms,instructure/canvas-lms,SwinburneOnline/canvas-lms,grahamb/canvas-lms,wye0220/shindig-canvas,usmschuck/canvas,grahamb/canvas-lms,shidao-fm/canvas-lms,dgynn/canvas-lms,whalejasmine/canvas-lms,venturehive/canvas-lms,sdeleon28/canvas-lms,djbender/canvas-lms,juoni/canvas-lms,fronteerio/canvas-lms,arrivu/arrivu-lms,Jyaasa/canvas-lms,HotChalk/canvas-lms,narigone/canvas,sfu/canvas-lms,skmezanul/canvas-lms,greyhwndz/canvas-lms,grahamb/canvas-lms,redconfetti/canvas-lms,leftplusrightllc/canvas-lms,gbleydon/canvas-lms,tgroshon/canvas-lms,jay3126/canvas-lms,loganrun/pincan,skmezanul/canvas-lms,wrdsb/canvas-lms,snehakachroo1/LSI_replica,greyhwndz/canvas-lms,AndranikMarkosyan/lms,narigone/canvas,loganrun/pincan,whalejasmine/canvas-lms,usmschuck/canvas,juoni/canvas-lms,HotChalk/canvas-lms,roxolan/canvas-lms,landonwilkins/canvas-lms,Rvor/canvas-lms,roxolan/canvas-lms,gbleydon/canvas-lms,efrj/canvas-lms,juoni/canvas-lms,antoniuslin/canvas-lms,eCNAP/CANVAS,venturehive/canvas-lms,tgroshon/canvas-lms,landonwilkins/canvas-lms,whalejasmine/canvas-lms,kyroskoh/canvas-lms,Rvor/canvas-lms,arrivu/arrivu-lms,arrivu/hoodemo,djbender/canvas-lms,whalejasmine/canvas-lms,Rvor/canvas-lms,ShreniiNepal/shrenii_lmp,usmschuck/canvas,landonwilkins/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,arrivu/qibla-ecampus,eCNAP/CANVAS,roxolan/canvas-lms,leftplusrightllc/canvas-lms,instructure/canvas-lms,dgynn/canvas-lms,snehakachroo1/LSI_replica,wrdsb/canvas-lms,wimemx/Canvas,snehakachroo1/LSI_replica,instructure/canvas-lms,Unow/canvas-lms,wrdsb/canvas-lms,antoniuslin/canvas-lms,shidao-fm/canvas-lms,ShreniiNepal/shrenii_lmp,va7map/canvas-lms,instructure/canvas-lms,greyhwndz/canvas-lms,instructure/canvas-lms,greyhwndz/canvas-lms,narigone/canvas,Jyaasa/canvas-lms,eCNAP/CANVAS,Unow/canvas-lms,snehakachroo1/LSI_replica,usmschuck/canvas,antoniuslin/canvas-lms,sdeleon28/canvas-lms,fronteerio/canvas-lms,HotChalk/canvas-lms,sfu/canvas-lms,samuels410/greatlakes-lms,skmezanul/canvas-lms,efrj/canvas-lms,arrivu/jigsaw-lms,instructure/canvas-lms,djbender/canvas-lms,utkarshx/canvas-lms,redconfetti/canvas-lms,wimemx/Canvas,arrivu/arrivu-lms,va7map/canvas-lms,AndranikMarkosyan/lms,fronteerio/canvas-lms,wye0220/shindig-canvas,narigone/canvas,sfu/canvas-lms,Rvor/canvas-lms,SwinburneOnline/canvas-lms,instructure/canvas-lms,matematikk-mooc/canvas-lms,matematikk-mooc/canvas-lms,arrivu/hoodemo,jay3126/canvas-lms,shidao-fm/canvas-lms,matematikk-mooc/canvas-lms,djbender/canvas-lms,redconfetti/canvas-lms,samuels410/greatlakes-lms,roxolan/canvas-lms,redconfetti/canvas-lms,AndranikMarkosyan/lms