Provide import functionality via frontend for reviewers

Description / Overview

In order to reduce overhead for developers and reduce minimum time needed between an exam and the correction, it would be beneficial if a reviewer could import the data himself via the frontend.

Use cases

• Reduces communication overhead and minimum time between exam and correction

Links / references

Feature checklist

• Backend:
  • provide endpoint /api/import/ that takes the json output of rusty-hektor that is currently loaded by the importer scipt
    • functionality from importer script can probably be reused
      • Currently the importer script uses logging, it would be good if (some of?) that output could be returned from the endpoint
• Frontend:
  • implement component that can be used to upload .json (see Components handling anonymous mapping file for file input)
  • send json to the /api/import/ endpoint