Block students from submitting after they leave the room

[jorg-vr]

Create a final submission button for users.

This allows user to mark a specific submission as a submission they want a teacher to look at.

The idea is that this cannot be undone by the student, only by the teacher.

These submissions can be used when building evaluations.

Teachers can then also confirm if a student has made a final submission, before allowing them to leave the room. (This requires a good overview page for the teacher)

This issue depends on #5548 being fixed first

[BTWS2]

Great feature request! For the time being I have to check this manually after each evaluation.

There should be a default (e.g. last one before the deadline). Some students will forget to mark a submission as final at the end of the evaluation.