Add lti consumer xblock modules to LTI REST endpoints

[robrap]

This allows LTI consumer xblock modules being hocked into get_course_lti_endpoints for
discovering LTI result/outcome endpoints.

This edx-platform change is required to complete testing of the xblock-lti-consumer upgrade being brought into the platform in this PR: https://github.com/edx/edx-platform/pull/14348

It also replaced the following PR: https://github.com/edx/edx-platform/pull/13639

NOTE: I am going to upgrade the sandbox with this branch.

Sandbox:

• Sandbox: https://robrap.sandbox.edx.org (provisioning in progress...)

[robrap]

Reviewers: Before this change, when I went to the following url:
https://robrap.sandbox.edx.org/courses/course-v1:edX+DemoX+Demo_Course/lti_rest_endpoints/
I saw the following result:

[]

Hopefully, we will have something different after I update the sandbox. :)

[robrap]

@xcompass @douglashall: After the changes when I navigate to:
https://robrap.sandbox.edx.org/courses/course-v1:edX+DemoX+Demo_Course/lti_rest_endpoints/
I see:

[{
  "lti_1_1_result_service_xml_endpoint": "https://robrap.sandbox.edx.org/courses/course-v1:edX+DemoX+Demo_Course/xblock/block-v1:edX+DemoX+Demo_Course+type@lti_consumer+block@1777e9cddf5f43a98f641521ae90c574/handler_noauth/outcome_service_handler",
  "display_name": "LTI Consumer",
  "lti_2_0_result_service_json_endpoint": "https://robrap.sandbox.edx.org/courses/course-v1:edX+DemoX+Demo_Course/xblock/block-v1:edX+DemoX+Demo_Course+type@lti_consumer+block@1777e9cddf5f43a98f641521ae90c574/handler_noauth/result_service_handler/user/{anon_user_id}"
}]

I'm concerned with /user/{anon_user_id} at the end of 'lti_2_0_result_service_json_endpoint'. Is this evidence of a defect in openedx/xblock-lti-consumer#22 ?

[robrap]

@xcompass @douglashall: At first this looked suspicious, but now I see that /user/{anon_user_id} has been hard-coded in that result for a long time:
https://github.com/edx/edx-platform/blob/18e3e095d106d3aba3683faf53819f825c2917ca/lms/djangoapps/courseware/views/views.py#L1087

So, all looks good. Feel free to add thumbs if you wish. Looks like this will finally be merging shortly.

[robrap]

jenkins run bokchoy

[douglashall]

👍

[dianakhuang]

👍 happy to see that the endpoint is working now!

[robrap]

Somehow this commit got lost in the shuffle with the consumer upgrade. I am working on it in this new PR: https://github.com/edx/edx-platform/pull/15478