feat: add waffle flag states rest api and util

[MaferMazu]

Description

This PR adds a util and a REST API to check whether the waffle flag related to authz (authz.enable_course_authoring) is enabled.

Those functions return a dictionary mapping scopes to their activation status:

• 'global' (bool): True if the global waffle flag is enabled.
• 'org' (bool): True if at least one organization-level override is enabled.
• 'course' (bool): True if at least one course-level override is enabled.

This PR is related to:

• fix: hide course authoring content when enable_course_authoring is off frontend-app-admin-console#176
• [Bug] Hide Authoring roles in the role assignment wizard when Authoring is disabled at platform, org, and course level #341
• [Bug] Authoring-related UI is visible in lists when the waffle flag is off #340

And try to solve:

same fix as #341 : we show Authoring UI if ANY Authoring related Waffle flag is ON. We hide it if ALL of them are OFF.

📌 We still need to modify the REST API endpoints to provide the correct information to the front end, but this is an effort to centralize the waffle flag information.

How to test

• Enter in http://local.openedx.io:8000/api/authz/v1/waffle-flag-states/
• You should be able to see a response that says if you have the waffle flag active or not in global, org, and course scope.

More about how to activate the waffle flags: openedx/openedx-platform#37985

More context on how it should work

Operator notes: https://openedx.atlassian.net/wiki/spaces/OEPM/pages/6331662350/RBAC+AuthZ+for+Course+Authoring+-+Operator+Release+Notes

Merge checklist:
Check off if complete or not applicable:

• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Fixup commits are squashed away
• Unit tests added/updated
• Manual testing instructions provided
• Noted any: Concerns, dependencies, migration issues, deadlines, tickets

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[MaferMazu]

I still need to add the tests, but that's the base.