Hide module model answers on lifesupport

[Mikael-Lenander]

Description

What?

Now also chapters that are marked as model answers for a module are hidden after the lifesupport time passes.

Why?

Model answers should be hidden after the course ends.

Should the message in the info tooltip inside a hidden chapter MODULE_MODEL_ANSWER_NOT_VISIBLE also be changed accordingly? Now it only says: "This chapter is hidden, since it contains model answers that have not been published yet." even if the course is ended.

Testing

Remember to add or update unit tests for new features and changes.

• How to test your changes in A-plus
• How to test accessibility

What type of test did you run?

• [ ] Accessibility test using the WAVE extension.
• [x] Django unit tests.
• [ ] Selenium tests.
• [ ] Other test. (Add a description below)
• [x] Manual testing.

Student wasn't able to see model chapters after setting lifesupport time to a past date.

Did you test the changes in

• [x] Chrome
• [ ] Firefox
• [ ] This pull request cannot be tested in the browser.

Translation

• [ ] Did you modify or add new strings in the user interface? (Read about how to create translation)

Programming style

• [x] Did you follow our style guides?
• [x] Did you use Python type hinting in all functions that you added or edited? (type hints for function parameters and return values)

Have you updated the README or other relevant documentation?

• [ ] documents inside the doc directory.
• [ ] README.md.
• [ ] Aplus Manual.
• [ ] Other documentation (mention below which documentation).

Is it Done?

• [ ] Reviewer has finished the code review
• [ ] After the review, the developer has made changes accordingly
• [ ] Customer/Teacher has accepted the implementation of the feature

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