issue406 add statistics to band class

[ElienVandermaesenVITO]

With the changes of Open-EO/openeo-geotrellis-extensions#406, the metadata of the assets have a bands will a field bands that contains statistics instead of the raster:bands field. When trying to download the results (j-25102008133547d8a8deeb00481658b0), an error happens: TypeError("Band.__new__() got an unexpected keyword argument 'statistics'") (r-2510211238334676a70a5ae8dd8ae81a)
Adding statistics to the Band class should fix this

[EmileSonneveld]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Chef's kiss.

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[soxofaan]

As mentioned IRL, I think this fix is at the wrong level. The Bands class in the python client is intentionally a very simple data class, to just cover the bare openEO-oriented band metadata that are relevant for the client code (which is currently just name, and maybe common name). Statistics is a bit too advanced at the moment and STAC-extension-specific.
If there is reason to increase the scope of this class, I would immediately go for a pystac based one, instead having to deal with incremental ad-hoc additions each time some lack of extra metadata support is uncovered.

If I understand correctly, the source of the error is this construct in openeo-geopyspark-driver:

                    asset["bands"] = [Band(**b) for b in asset["bands"]]

A better fix would be to avoid the naive "just push in everything" approach of Band(**)
or to make a richer Band subclass that does support extra metadata aspects provided by openeo-geopyspark-driver