chaining save_result does not work for JSON, CSV assets etc

[bossie]

save_result processes can be chained to output assets in multiple formats e.g.

(data_cube
  .save_result("GTiff")
  .save_result("netCDF")
  .download())

this works for images like GeoTIFF + netCDF but not for e.g. aggregate_spatial output in JSON + CSV.

Can be traced back to aliasing on this line where the last save_result node's format will override previous ones:

openeo-python-driver/openeo_driver/ProcessGraphDeserializer.py

Line 741 in 46b9acc

data.set_format(format, options)

[bossie]

TODO:

• enable skipped test added in Open-EO/openeo-geopyspark-driver@02268c3

[soxofaan]

FYI (as discussed), this construct

cube
  .save_result("GTiff")
  .save_result("netCDF")

is conceptually shaky: save_result returns a boolean per current spec.
Related ticket for openeo python client to disallow this: Open-EO/openeo-python-client#402