lti2 course and account nav placements

fixes PLAT-658 PLAT-660 PLAT-661

test plan:
setup:
fixes PLAT-658 PLAT-660 PLAT-661

test plan:
*setup:
register an lti tool using the following url template
/accounts/#{account_id}/lti/tool_proxy_registration?
tool_consumer_url=http://lti-tool-provider-example.herokuapp.com/tool_proxy

ignore the canvaception during the registration

*testing:
there should be course and account nav placements for the tool

Change-Id: Ie02fffdc3a1ede70216db2b21d9f4bd17f53f36d
Reviewed-on: https://gerrit.instructure.com/42094
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Reviewed-by: Brad Humphrey <brad@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>