Migrate to general data cube definition

[m-mohr]

This goes through the existing processes and makes changes so that, if applicable, they work with vector cubes.

Tasks:

• [x] Replace raster-cube subtype with datacube
• [x] Define datacube dimension minimum requirements
• [x] Update tests
• [x] Update descriptions (e.g. check mentioning of "pixel values" or raster data cubes)
• [x] Check geojson parameters (and also allow vector-cubes)
• [x] ~Add guidelines how geojson should be converted into a vector-cube (as we have geojson as input data type it might be the only file format for which we describe the actual import procedure)~ -> I'll keep this as a separate PR, tracked by #346
• [x] Update dimension types, e.g. in add_dimension
• [x] Update subtype-schemas.json
• Process specific:
  • [x] Update aggregate_spatial with all its flaws and proposed changes
  • [x] load_collection/load_results: Update descriptions to reflect vector use cases
  • [x] filter_bbox/spatial: Update description to reflect vector use cases (only include values that are fully included in the given extent?)
  • [x] What dimension types are required in ard_normalized_radar_backscatter and sar_backscatter? spatial + bands?
  • [x] merge_cubes needs new/more examples
  • [x] Does it make sense to extend climatological_normal from raster-cubes to general datacubes?

[m-mohr]

This is ready for review! 🥳

[m-mohr]

For another issue: Should we change the vector_ prefix for the vector-related processes to something else?

Edit: Thinking a bit more about it, I think vector_ is fine. We still have a vector data cube as input, only the dimension is using the geometry terminology. As the prefixes do usually reflect the type of data you are passing in (i.e. vector data cube), we can stick with the names. Also to preserve a bit of backward compatibility with some rare implementations.

[soxofaan]

For another issue: Should we change the vector_ prefix for the vector-related processes to something else?

Also: let's move that question to another issue, to unblock #382

[m-mohr]

This is also ready for final review. I hope that I have fixed all open issues sufficiently. If you see minor things that we can fix quickly, please mention them here. If you see larger issues to be discussed, maybe open a separate issue so that we can merge this and then work in smaller PRs that are easier to handle.

Additionally, the schema for vector data cubes has changed due to the changes in the other PRs (API, STAC etc.):

                {
                    "type": "object",
                    "subtype": "datacube",
                    "dimensions": [
                        {
                            "type": "geometries"
                        }
                    ]
                }

So the type is now geometries instead of vector.

@soxofaan @mkadunc @aljacob @clausmichele @jdries @dthiex @LukeWeidenwalker @pierocampa

[m-mohr]

Also: let's move that question to another issue, to unblock #382

See #397

[m-mohr]

@aljacob The naming is discussed in another issue: https://github.com/Open-EO/openeo-api/issues/479