[Tmp] JSON export filtering

Felix Blankerequested to merge
felix_bonn/akplanning:feature/export-filtering into main

This MR adds a new admin form to control the exported JSON data (e.g. filter out AKs by category)

Only temporary as some intricacies of the filtering are not yet addressed:

  1. data consistency checks had to be disabled for now
  2. unit test cover do not yet cover the filtering

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