add post action for resource_selection routes
add post action for resource_selection routes

fixes PLAT-2929

test plan:

try and do a launch from a group rce

it should work

Change-Id: Ie0143becf6e5b7744978d8599baa1027d1e52aa4
Reviewed-on: https://gerrit.instructure.com/133782
QA-Review: Jeremy Putnam <b030d6d6f199f844ec424882be473c2ab9adc93b@instructure.com>
Reviewed-by: Weston Dransfield <e9203059795dc94e28a8831c65eb7869e818825e@instructure.com>
Tested-by: Jenkins
Product-Review: Nathan Mills <10b0771d20c18ad0d98c1d000665e443052b40b0@instructure.com>

sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms