Resource Links Create/Edit/Delete Trigger Live Event

[braysch]

There were no live events for Lti::ResourceLink. This adds lti_resource_link_created and lti_resource_link_updated events so downstream consumers can react when Canvas encounters a new LTI link in a course.

• Added lti_resource_link_created and lti_resource_link_updated event methods to Canvas::LiveEvents with a shared
  payload helper
• Registered Lti::ResourceLink in LiveEventsObserver and wired after_create/after_update in
  Canvas::LiveEventsCallbacks
• Soft delete (.destroy) fires lti_resource_link_updated with workflow_state: "deleted" — no separate delete event

Payload includes: resource_link_id, resource_link_uuid, lookup_uuid, context_id, context_type,
context_external_tool_id, url, title, workflow_state

Verified with: unit tests, observer integration tests, and manual testing via fake Kinesis server

[JoshBothell]

Ryker has indicated that we are good to go ahead with these PRs to Instructure. In his words "you’re more familiar with the code at this point anyways."

This looks pretty much exactly the same as the new events I added for quizzes w/o assignment. I think we are good to send it over to Instructure. Justin also said that they should get auto assigned and we don't need to specifically notify him when we open a PR to Instructure.