Outcomes Import API: Add endpoint to query migration issues

The content migrations for outcomes importing are not scoped to an account
or a course, since the academic benchmarks standards are imported globally
per shard.

Fixes CNVS-21782

Test Plan:

    1.  Kick off an outcomes import task
        - curl -H 'Authorization: Bearer <api-key>'
            --data 'guid=<some-guid>'
            'http://<canv-domain>/api/v1/global/outcomes_import'
    2.  Query it through this endpoint and make sure it works
        - curl -H 'Authorization: Bearer <api-key>'
            'http://<canv-domain>/api/v1/global/outcomes_import/migration_status/<migration-id>'

Change-Id: I8ff3a5206bb7aa5f97d615912c60341fedcaf855
Reviewed-on: https://gerrit.instructure.com/58034
Tested-by: Jenkins
Reviewed-by: Cameron Sutter <csutter@instructure.com>
QA-Review: Michael Hargiss <mhargiss@instructure.com>
Product-Review: Benjamin Porter <bporter@instructure.com>

app/controllers/outcomes_import_api_controller.rb

@@ -18,6 +18,7 @@
 
 class OutcomesImportApiController < ApplicationController
   include Api::V1::Outcome
+  include Api::V1::ContentMigration
 
   before_filter :require_user, :can_manage_global_outcomes, :has_api_config
 
@@ -48,6 +49,17 @@ class OutcomesImportApiController < ApplicationController
     end
   end
 
+  def migration_status
+    return render json: { error: "must specify a migration id" } unless params[:migration_id]
+
+    begin
+      cm = ContentMigration.find(params[:migration_id])
+      render json: content_migration_json(cm, @current_user, session)
+    rescue ActiveRecord::RecordNotFound => e
+      render json: { error: "no content migration matching id #{params[:migration_id]}" }
+    end
+  end
+
   protected
 
   def can_manage_global_outcomes

config/routes.rb

@@ -1572,6 +1572,7 @@ CanvasRails::Application.routes.draw do
       # get  "global/outcomes_import/list/:guid", action: :list
       get  "global/outcomes_import/available",  action: :available
       post "global/outcomes_import",            action: :create
+      get  "global/outcomes_import/migration_status/:migration_id", action: :migration_status
     end
 
     scope(controller: :group_categories) do