Update research field mapping

• to take effect only on the level of this YAML structure #5 (closed)
• if emtpy strings occur -> map to "Unkown"
• if non-empty strings occur that are not listed in the YAML file
  • log them & communicate
  • map to "Other" (potentially rerun harvesting after updating the mapping YAML)
• exceptions:
  • Data published at GFZ in years >= 2021 (PoF IV) can be mapped to "Earth and Environment"
    • explanation: in PoF I - PoF III (years < 2021), GFZ was funded within RFs Energy and E&E. Since PoF IV the only RF assigned to GFZ is E&E