Add export extra work functionality

Description

• When looking at a specific extra work (eg. extra-work/1) an export declarations button has been added

• Pressing this button results in an export of all the declarations for that extra work (sorted by student number)

• Added a page displaying all the declarations (declarations/all)

• Added the ability to export all of these declarations

Related Issues

• Resolves #61 (closed)

Checklist

• I have added a changelog entry to reflect the significant changes I made.

changed milestone to %Working v2.0

added difficultymedium ui + 1 deleted label

requested review from @rbackx

assigned to @toberhuber

added 1 commit

• 01b87c7e - Fix failing test

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changed the description

added 1 commit

• 71459d4d - Add all declarations page + All declarations export

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approved this merge request

started a merge train

merged

mentioned in commit 8eccd819

unassigned @toberhuber