Feature: Add user-selected and generated files to the FSKX archive

[schuelet]

Files generated in a FSK-lab workflow are added to the final FSKX archive.

Current state of development

• files saved in the archive:
  • plot image
  • output parameters marked as FILE in Metadata (generated during model execution)
  • resource files added in the Editor (only whitelisted formats end up in fskx archive)
  • workspace (and soon the hdf5 file containing the output parameters of a model)
• files not currently saved in archive:
  • joiner image
  • any other files generated during the model execution
  • files not on whitelist, like documents or papers

[schuelet]

adding the joiner image is ok, the other points I think should go. Maybe we increase the whitelist a bit but adding simply everything that a model could create during execution is ill-advised.