add lti launch params and substitutions

test plan:
  - create a tool with ContentItemSelectionResponse
  - it should send the parameter 'tool_consumer_instance_contact_email'
  - it should substitute the parameter $Canvas.user.prefersHighContrast

fixes PLAT-622

Change-Id: If55d0a1b488f82a90c8aa620fd037f7e7c7b0272
Reviewed-on: https://gerrit.instructure.com/40703
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Nathan Mills <nathanm@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>