Making a subsection available as prerequisite doesn't inmediately propagate to other sections

[DanielVZ96]

When you mark a subsection as available for being a prerequisite, it sometimes needs a refresh in order to be able to be visible as prerequisite for other sections.

In the following video you can see that the "Grade submission to ELIS settings" subsection is marked as a prerequisite. but then it doesn't appear available as a prerequisite in another subsection.

prereq-bu.webm

I tried to find a fix for the issue, but I think it has to do with the prerequisites being loaded as part of a section in the state used by the modal, so it isn't shared across other sections, so the only quick fix I could find was refreshing the whole state which is less than ideal.

[itsjeyd]

Draft PR for reference: open-craft#64