[Feature-first refactor] Add support for role/user based access

[iamdharmesh]

Description of the Change

PR adds support for role- and user-based access control to the ClassifiAI features. It also includes functionality for user-based opt-out, allowing users to choose not to use the specific feature if they prefer not to or if they dislike it.

This PR adds work of PR #606 to new feature-first refactoring branch.

How to test the Change

1. Enable role-based access to the feature.
2. Select roles in the allowed roles to provide access to that feature.
3. Verify that only the selected roles have access to that feature.
4. Enable user-based access to the feature.
5. Select the user in the allowed users to provide access to that feature.
6. Verify that the selected user has access to that feature.
7. Enable user-based opt-out for the feature.
8. Go to the user profile and verify that you see the checkbox for that feature to opt out of using it.
9. Check the opt-out checkbox and save.
10. Verify that access to that feature has been disabled.
11. Uncheck the opt-out checkbox to opt back in to the feature.
12. Verify that the user now has access to that feature.
13. Follow these steps for each ClassifAI feature.

Changelog Entry

Added - Role and user-based access control for features

Credits

Props @iamdharmesh

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[Sidsector9]

Thanks a lot @iamdharmesh for accommodating these changes! Code looks good and tests well. Approving 👍