Implement customizable classes (attempt 2)

[TiBiBa]

Provide a general summary of your changes in the Title of the PR

Description
In this PR we implement customizable classes. Enabling teachers to select specific adventures, hide example programs and/or hide levels. This feature will allow teachers to customize their teaching and restrict students to specific levels and/or adventures helping the teaching. We also fix a small bug where the incorrect active page on the menubar was shown.

Fix for
This PR fixed #1299 and fixed #1304.

How to test
Log in as a teacher account and navigate to a class. Choose the "customize class" button and select preferences for each level. Then, on a student account (enrolled to this class) navigate to the levels for which preferences where selected and notice the created restrictions.

Checklist

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[Felienne]

Hi @TiBiBa,

The overview looks great, just a few small UX issues:

• There is no back button to go back to classes overview
• Can we highlight the current level in the buttons (make it blue or something) I think that can replace the little "instellingen" header

Now by default all tickmarks are off:

That is a weird default because I would say conceptually all adventures are "on" at the start. Can we turn all marks on? Or are all adventure off by default for a new class?

[Felienne]

I am not sure I love the name preferences because we have been calling it customizations and preferences is quite generic. Shall we rename the table customization or class-customization?

[TiBiBa]

That would indeed be more straight forward. Will rename all variables (and the db) into customizations.

[TiBiBa]

Hi @TiBiBa,

The overview looks great, just a few small UX issues:

• There is no back button to go back to classes overview
• Can we highlight the current level in the buttons (make it blue or something) I think that can replace the little "instellingen" header

Now by default all tickmarks are off:

That is a weird default because I would say conceptually all adventures are "on" at the start. Can we turn all marks on? Or are all adventure off by default for a new class?

I will implement a back button and change the color of the active button (in combination with removing the header). By default they are all turned off (if any settings exist for the class/level combination). If no restriction exists for the class/level than all adventures are shown automatically.