feat: enable markdown to olx conversion

[Anas12091101]

Description

This PR enables the conversion from Markdown to OLX. The reverse conversion (OLX to Markdown) has been deferred for now, as it would require implementing a dedicated OLX-to-Markdown converter, which may take additional time. We plan to address that in a future update to ensure this change is merged before the Ulmo cut.

Useful information to include:

• Which user roles will this change impact? "Course Author", "Developer"
• Include screenshots for changes to the UI (ideally, both "before" and "after" screenshots, if applicable).

In Course
https://github.com/user-attachments/assets/cafee2fe-5445-4ec5-b90a-8b2d9b54d9f3

In Library
https://github.com/user-attachments/assets/98f45954-2d11-4dec-abcc-cc75d537882a

Supporting information

#1920
https://github.com/mitodl/hq/issues/8729

Testing instructions

• Create a new problem or edit an existing one that was originally created using the Markdown editor.
• Verify that the "Switch to Advanced Editor" button is displayed in the Settings sidebar on the right.
• Make some edits to the Markdown content, then click the "Switch to Advanced Editor" button and confirm the action in the confirmation modal.
• Verify that the editor switches to the OLX editor, and that the content is correctly converted to OLX format.

Other information

Include anything else that will help reviewers and consumers understand the change.

• Does this change depend on other changes elsewhere?
• Any special concerns or limitations? For example: deprecations, migrations, security, or accessibility.

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).
• Deprecated propTypes, defaultProps, and injectIntl patterns are not used 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.
• Imports avoid using ../. To import from parent folders, use @src, e.g. import { initializeMocks } from '@src/testUtils'; instead of from '../../../../testUtils'

[openedx-webhooks]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.69%. Comparing base (8fe5fb6) to head (f3e2511).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2518   +/-   ##
=======================================
  Coverage   94.68%   94.69%           
=======================================
  Files        1203     1203           
  Lines       26865    26876   +11     
  Branches     6026     6032    +6     
=======================================
+ Hits        25438    25449   +11     
  Misses       1357     1357           
  Partials       70       70           

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[bradenmacdonald]

This seems to work fine if I haven't saved the problem, but when I edit an existing (saved, published) markdown problem in a library, I don't see the option to convert it:

[bradenmacdonald]

Can we move this editorObject down inside the else { clause?

[bradenmacdonald]

This is fine, but I would have preferred we pass the editorRef around using a ProblemEditorContext instead of prop drilling.