Add deep linking route for "groups" context

Closes PLAT-5607

Test Plan:
- Install the MS Teams app in a course
- Add a student to that course and add
  them to a group
- Act as the student
- Click the the calendar in the global navigation
  and create a new event
- In the new events modal select the group
  the student belongs to for the "Calendar"
  input
- Click "more options"
- In the RCE, verify you can emberd a MS teams meeting

Change-Id: I2567c9db1d1ceb2a2a80fc1c595d1e5ed528d91e
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/230070
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Evan Battaglia <ebattaglia@instructure.com>
Reviewed-by: Jacob Burroughs <jburroughs@instructure.com>
Reviewed-by: Tucker Mcknight <tmcknight@instructure.com>
QA-Review: Evan Battaglia <ebattaglia@instructure.com>
Product-Review: Weston Dransfield <wdransfield@instructure.com>

config/routes.rb

@@ -500,7 +500,7 @@ CanvasRails::Application.routes.draw do
   get 'external_content/retrieve/oembed' => 'external_content#oembed_retrieve', as: :external_content_oembed_retrieve
   get 'external_content/cancel/:service' => 'external_content#cancel', as: :external_content_cancel
 
-  %w(account course).each do |context|
+  %w(account course group).each do |context|
     prefix = "#{context}s/:#{context}_id"
     post "#{prefix}/deep_linking_response", controller: 'lti/ims/deep_linking', action: :deep_linking_response, as: "#{context}_deep_linking_response"
   end