use the correct url for lit sessionless launch urls

test plan
 - create an assignment with a different launch url then the default for a tool
 - launch the assignment via sessionless launch
 - it should launch to the configured url

 - repeat for module items

fixes PLAT-456

Change-Id: Iafc44dc255dbf1f9917f09bf7ef8959a7c8b90d4
Reviewed-on: https://gerrit.instructure.com/32360
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Bracken Mosbacker <bracken@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>
QA-Review: Nathan Rogowski <nathan@instructure.com>