[BD-27][TNL-7891][BB-3539] Remove Empty Sections from cc2olx Conversions - ContextModuleSubHeader

[shimulch]

This PR fixes an issue related to empty sections while there are canvas items with content type ContextModuleSubHeader. With this PR, cc2olx will treat these types of items as subsections and collapse related (consecutive) items under it as verticals.

JIRA tickets:

• https://tasks.opencraft.com/browse/BB-3539
• https://openedx.atlassian.net/browse/TNL-7891

Discussions:

Dependencies: None

Screenshots:

Sandbox URL:

Merge deadline: None

Testing instructions:

1. Pull this PR.
2. Find a canvas imscc file that contains ContextModuleSubHeader, you can use the updated fixture with this PR.
3. Convert using cc2olx.
4. Check that item after ContextModuleSubHeader collapsed into it as verticals.

Author notes and concerns:
N/A

Reviewers

• @kaizoku
• edX reviewer[s] TBD

[openedx-webhooks]

Thanks for the pull request, @shimulch! I've created BLENDED-765 to keep track of it in Jira. More details are on the BD-27 project page.

When this pull request is ready, tag your edX technical lead.

[kaizoku]

Should we run this in all cases, or only run this transformation for canvas flavored common cartridges?
We can check if course_settings/canvas_export.txt exists to determine if this is a canvas flavored CC.
Canvas writes this file to determine if it's from a canvas export.

[shimulch]

@kaizoku, Thanks for the suggestion. Yeah this approach would be better. I've updated my PR.

[kaizoku]

Thanks for the PR @shimulch.
This works well for me on the affected courses and isn't causing issues with other courses. 👍

• [✓] I tested this: (converted courses affected and not affected by issues, examined outlines and course structure in studio/lms)
• [✓] I read through the code
• [n/a] I checked for accessibility issues
• [n/a] Includes documentation