Deprecate ENABLE_GRADING_METHOD_IN_PROBLEMS & Add Grading Method view

[irtazaakram]

Description

This pull request does two things:

1. Deprecates the ENABLE_GRADING_METHOD_IN_PROBLEMS toggle
2. Adds the missing Grading Method view

Background / Rationale:

• The grading method view was previously being implemented in [frontend-lib-content-components](https://github.com/openedx-unsupported/frontend-lib-content-components), but that library has since been deprecated.
• The code for the view is adapted from the closed PR in the deprecated repo: [PR #430](feat: add grading method field in problem editor openedx-unsupported/frontend-lib-content-components#430).

Impact on user roles:

• Course Authors / Studio users: Will now see the grading method displayed in problem block settings and can change it.
• Developers: Removes reliance on the deprecated feature toggle.

UI Changes:

Before:

After:

Supporting information

• Previous implementation (deprecated): frontend-lib-content-components PR #430

Testing instructions

openedx-unsupported/frontend-lib-content-components#430 (comment)
openedx-unsupported/frontend-lib-content-components#430 (comment)

Other information

openedx/edx-platform#37811

Best Practices Checklist

We're trying to move away from some deprecated patterns in this codebase. Please
check if your PR meets these recommendations before asking for a review:

• Any new files are using TypeScript (.ts, .tsx).
• Avoid propTypes and defaultProps in any new or modified code.
• Tests should use the helpers in src/testUtils.tsx (specifically initializeMocks)
• Do not add new fields to the Redux state/store. Use React Context to share state among multiple components.
• Use React Query to load data from REST APIs. See any apiHooks.ts in this repo for examples.
• All new i18n messages in messages.ts files have a description for translators to use.
• Avoid using ../ in import paths. To import from parent folders, use @src, e.g. import { initializeMocks } from '@src/testUtils'; instead of from '../../../../testUtils'

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.99%. Comparing base (2209242) to head (8605435).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2795   +/-   ##
=======================================
  Coverage   94.99%   94.99%           
=======================================
  Files        1256     1256           
  Lines       28800    28814   +14     
  Branches     6538     6541    +3     
=======================================
+ Hits        27358    27372   +14     
+ Misses       1384     1371   -13     
- Partials       58       71   +13     

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