Fix bug caused by cached representation in cohomology classes

[miguelmarco]

📚 Description

Fixes #35649

Adds the parent to the creation of cohomology classes, so they are not confused between different parents.

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[miguelmarco]

Should the issue be changed to positive review too?

[mkoeppe]

No need for a status label on the issue; I've removed it.
It will be closed as completed automatically when the PR is merged.

[tscrim]

Minor point, but I don't think we should call the input parent as it is not the parent (which would be the not-(yet-)coded cohomology ring). Instead it should be something like cdga. That way it will also be future compatible.

[github-actions]

Documentation preview for this PR (built with commit b3d322e) is ready! 🎉

[tscrim]

Thank you. LGTM.

[dimpase]

b3d322e
added extra trailing space - how didn't you see this on the linters?

[dimpase]

Perhaps the linter only shows the 1st trailing whitespace it finds, and so it didn't show this changed file