[SE-3440] Adds grade cutoffs to gradebook grading information

[nizarmah]

Adds course grade_cutoffs to the /api/grades/v1/gradebook/{course_id}/grading-info.

JIRA tickets: SE-3440

Upstream Pull Request: https://github.com/edx/edx-platform/pull/25978

Sandbox URL:

• LMS: https://pr305.sandbox.stage.opencraft.hosting/
• Studio: https://studio.pr305.sandbox.stage.opencraft.hosting/

Testing instructions:

Run the following function and verify that grade_cutoffs is highlighted 😃

curl --request POST \
  --insecure --url https://pr305.sandbox.stage.opencraft.hosting/oauth2/access_token/ \
  --header 'content-type: multipart/form-data;' \
  --form grant_type=client_credentials \
  --form client_id=LgIomajnBojAT0l65g0jFWxiJTODMejydpoDQDPR \
  --form client_secret=qO7Ng8OcwB4tQFbXilDdKIR2uADwfEJNGanSVaDieoq4n39XTExuEpN1qV4yCPiKpyFjKT7y1Awwsy17aCCNNtPl7F8YPYeu0oHV7WtHWOyZCKQ01Bj7POe2QDiZWZeF \
  | awk '{print substr($9, 2, length($9)-3)}' \
  | xargs -I "TOKEN" sh -c \
    "curl --request GET \
          --insecure --url 'https://pr305.sandbox.stage.opencraft.hosting/api/grades/v1/gradebook/course-v1:edX+DemoX+Demo_Course/grading-info' \
          --header 'authorization: Bearer TOKEN'" \
  | grep "grade_cutoff"

You can also update the grading scale for the Demo course, and verify those changes are reflected.

Author notes and concerns:

1. If you'd prefer that I add a separate API endpoint for this, please let me know 👍🏼
2. I know I shouldn't be sharing credentials, but this is a sandbox 🤷🏼‍♂️

Reviewers

• @s0b0lev

[s0b0lev]

@nizarmah 👍 looks good

• I tested this: call API, change the grading scale - changes were reflected
• I read through the code